mysql connector/j 5.1 developer guide

MySQL Connector/J 5.1 Developer Guide

Abstract

This manual describes how to install, configure, and develop database applications using MySQL Connector/J 5.1, aJDBC driver for communicating with MySQL servers. It also contains information on earlier versions of Connector/J.

Support EOL for MySQL Connector/J 5.1

Per Oracle's Lifetime Support policy, as of Feb 9th, 2021, MySQL Connector/J 5.1 seriesis covered under Oracle Sustaining Support. Users are encouraged to upgrade to MySQLConnector/J 8.0 series.

For notes detailing the changes in each release of Connector/J 5.1, see MySQL Connector/J 5.1 Release Notes.

For legal information, see the Legal Notices.

For help with using MySQL, please visit the MySQL Forums, where you can discuss your issues with other MySQLusers.

Licensing information. This product may include third-party software, used under license. If you are using aCommercial release of MySQL Connector/J 5.1, see the MySQL Connector/J 5.1 Commercial License InformationUser Manual for licensing information, including licensing information relating to third-party software that may beincluded in this Commercial release. If you are using a Community release of MySQL Connector/J 5.1, see theMySQL Connector/J 5.1 Community License Information User Manual for licensing information, including licensinginformation relating to third-party software that may be included in this Community release.

Document generated on: 2022-01-17 (revision: 71722)

https://docs.oracle.com/cd/E17952_01/connector-j-5.1-relnotes-en/

http://forums.mysql.com

https://docs.oracle.com/cd/E17952_01/connector-j-5.1-license-com-en/

https://docs.oracle.com/cd/E17952_01/connector-j-5.1-license-com-en/

https://docs.oracle.com/cd/E17952_01/connector-j-5.1-license-gpl-en/

Table of ContentsPreface and Legal Notices .................................................................................................................. v1 Overview of MySQL Connector/J ..................................................................................................... 12 Connector/J Versions, and the MySQL and Java Versions They Require ........................................... 3

2.1 Connector/J Release Notes and Change History .................................................................... 42.2 Java Versions Supported ...................................................................................................... 4

3 Connector/J Installation ................................................................................................................... 53.1 Installing Connector/J from a Binary Distribution .................................................................... 53.2 Installing the Driver and Configuring the CLASSPATH ............................................................. 53.3 Upgrading from an Older Version .......................................................................................... 6

3.3.1 Upgrading to MySQL Connector/J 5.1.x ...................................................................... 73.3.2 JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer ........................ 73.3.3 Upgrading from MySQL Connector/J 3.0 to 3.1 ........................................................... 7

3.4 Installing from Source ........................................................................................................... 93.5 Testing Connector/J ............................................................................................................ 13

4 Connector/J Examples ................................................................................................................... 155 Connector/J (JDBC) Reference ...................................................................................................... 17

5.1 Driver/Datasource Class Name ........................................................................................... 175.2 Connection URL Syntax ...................................................................................................... 175.3 Configuration Properties for Connector/J .............................................................................. 19

5.3.1 Connection/Authentication ........................................................................................ 205.3.2 Networking .............................................................................................................. 225.3.3 High Availability and Clustering ................................................................................ 235.3.4 Security ................................................................................................................... 265.3.5 Performance Extensions ........................................................................................... 295.3.6 Debugging/Profiling .................................................................................................. 355.3.7 Miscellaneous .......................................................................................................... 395.3.8 The useConfigs Option and the Configuration Property Files ...................................... 53

5.4 JDBC API Implementation Notes ......................................................................................... 545.5 Java, JDBC and MySQL Types ........................................................................................... 575.6 Using Character Sets and Unicode ...................................................................................... 605.7 Connecting Securely Using SSL .......................................................................................... 615.8 Connecting Using Unix Domain Sockets .............................................................................. 655.9 Connecting Using Named Pipes .......................................................................................... 655.10 Connecting Using PAM Authentication ............................................................................... 665.11 Source/Replica Using Replication with ReplicationConnection ............................................. 675.12 Mapping MySQL Error Numbers to JDBC SQLState Codes ................................................ 67

6 JDBC Concepts ............................................................................................................................. 756.1 Connecting to MySQL Using the JDBC DriverManager Interface ....................................... 756.2 Using JDBC Statement Objects to Execute SQL ............................................................... 766.3 Using JDBC CallableStatements to Execute Stored Procedures ..................................... 776.4 Retrieving AUTO_INCREMENT Column Values through JDBC ................................................ 80

7 Connection Pooling with Connector/J ............................................................................................. 858 Multi-Host Connections .................................................................................................................. 89

8.1 Configuring Server Failover ................................................................................................. 898.2 Configuring Load Balancing with Connector/J ...................................................................... 928.3 Configuring Source/Replica Replication with Connector/J ...................................................... 948.4 Advanced Load-balancing and Failover Configuration ........................................................... 98

9 Using the Connector/J Interceptor Classes ................................................................................... 10110 Using Logging Frameworks with SLF4J ...................................................................................... 10311 Using Connector/J with Tomcat .................................................................................................. 10512 Using Connector/J with JBoss .................................................................................................... 107

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13 Using Connector/J with Spring ................................................................................................... 10913.1 Using JdbcTemplate .................................................................................................... 11013.2 Transactional JDBC Access ............................................................................................ 11113.3 Connection Pooling with Spring ....................................................................................... 113

14 Using Connector/J with GlassFish .............................................................................................. 11514.1 A Simple JSP Application with GlassFish, Connector/J and MySQL ................................... 11614.2 A Simple Servlet with GlassFish, Connector/J and MySQL ................................................ 118

15 Troubleshooting Connector/J Applications ................................................................................... 12316 Known Issues and Limitations .................................................................................................... 13117 Connector/J Support .................................................................................................................. 133

17.1 Connector/J Community Support ..................................................................................... 13317.2 How to Report Connector/J Bugs or Problems ................................................................. 133

Index .............................................................................................................................................. 135

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Preface and Legal NoticesThis manual describes how to install, configure, and develop database applications using MySQLConnector/J 5.1, the JDBC driver for communicating with MySQL servers. It also contains information onearlier versions of Connector/J.

Legal Notices

Copyright © 1998, 2022, Oracle and/or its affiliates.

This software and related documentation are provided under a license agreement containing restrictionson use and disclosure and are protected by intellectual property laws. Except as expressly permittedin your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast,modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by anymeans. Reverse engineering, disassembly, or decompilation of this software, unless required by law forinteroperability, is prohibited.

The information contained herein is subject to change without notice and is not warranted to be error-free.If you find any errors, please report them to us in writing.

If this is software or related documentation that is delivered to the U.S. Government or anyone licensing iton behalf of the U.S. Government, then the following notice is applicable:

U.S. GOVERNMENT END USERS: Oracle programs (including any operating system, integratedsoftware, any programs embedded, installed or activated on delivered hardware, and modifications ofsuch programs) and Oracle computer documentation or other Oracle data delivered to or accessed byU.S. Government end users are "commercial computer software" or "commercial computer softwaredocumentation" pursuant to the applicable Federal Acquisition Regulation and agency-specificsupplemental regulations. As such, the use, reproduction, duplication, release, display, disclosure,modification, preparation of derivative works, and/or adaptation of i) Oracle programs (including anyoperating system, integrated software, any programs embedded, installed or activated on deliveredhardware, and modifications of such programs), ii) Oracle computer documentation and/or iii) other Oracledata, is subject to the rights and limitations specified in the license contained in the applicable contract.The terms governing the U.S. Government's use of Oracle cloud services are defined by the applicablecontract for such services. No other rights are granted to the U.S. Government.

This software or hardware is developed for general use in a variety of information managementapplications. It is not developed or intended for use in any inherently dangerous applications, includingapplications that may create a risk of personal injury. If you use this software or hardware in dangerousapplications, then you shall be responsible to take all appropriate fail-safe, backup, redundancy, and othermeasures to ensure its safe use. Oracle Corporation and its affiliates disclaim any liability for any damagescaused by use of this software or hardware in dangerous applications.

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Chapter 1 Overview of MySQL Connector/JMySQL provides connectivity for client applications developed in the Java programming language withMySQL Connector/J, a driver that implements the Java Database Connectivity (JDBC) API.

MySQL Connector/J is a JDBC Type 4 driver. Different versions are available that are compatible with theJDBC 3.0 and JDBC 4.x specifications (see Chapter 2, Connector/J Versions, and the MySQL and JavaVersions They Require). The Type 4 designation means that the driver is a pure Java implementation ofthe MySQL protocol and does not rely on the MySQL client libraries.

For large-scale programs that use common design patterns of data access, consider using one of thepopular persistence frameworks such as Hibernate, Spring's JDBC templates or MyBatis SQL Maps toreduce the amount of JDBC code for you to debug, tune, secure, and maintain.

Key Topics

• For installation instructions for Connector/J, see Chapter 3, Connector/J Installation.

• For help with connection strings, connection options, and setting up your connection through JDBC, seeSection 5.3, “Configuration Properties for Connector/J”.

• For information on connection pooling, see Chapter 7, Connection Pooling with Connector/J.

• For information on multi-host connections, see Chapter 8, Multi-Host Connections.

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Chapter 2 Connector/J Versions, and the MySQL and JavaVersions They Require

Table of Contents2.1 Connector/J Release Notes and Change History ............................................................................ 42.2 Java Versions Supported .............................................................................................................. 4

Two versions of MySQL Connector/J are available:

• Connector/J 5.1 is a Type 4 pure Java JDBC driver, which conforms to the JDBC 3.0, 4.0, 4.1, and4.2 specifications. It provides compatibility with all the functionality of MySQL, including 5.6, 5.7 and8.0. Connector/J 5.1 provides ease of development features, including auto-registration with the DriverManager, standardized validity checks, categorized SQLExceptions, support for large update counts,support for local and offset date-time variants from the java.time package, support for JDBC-4.x XMLprocessing, support for per connection client information, and support for the NCHAR, NVARCHAR andNCLOB data types.

• Connector/J 8.0 is a Type 4 pure Java JDBC 4.2 driver for the Java 8 platform. It provides compatibilitywith all the functionality of MySQL 5.6, 5.7, and 8.0. See MySQL Connector/J 8.0 Developer Guide fordetails.

Note

MySQL Connector/J 8.0 is highly recommended for use with MySQL Server 8.0,5.7, and 5.6. Please upgrade to MySQL Connector/J 8.0.

The following table summarizes the Connector/J versions available, along with the compatibility informationfor different versions of JDBC, MySQL Server, and Java, as well as the support status for each of theConnector/J versions:

Table 2.1 Summary of Connector/J Versions

Connector/Jversion

JDBC version MySQL Serverversion

JRE Required JDK Requiredfor Compilation

Status

5.1 3.0, 4.0, 4.1, 4.2 5.61, 5.71, 8.01 JRE 5 or higher1 JDK 5.0 ANDJDK 8.0 orhigher2, 3

Generalavailability

8.0 4.2 5.6, 5.7, 8.0 JRE 8 or higher JDK 8.0 orhigher2

Generalavailability.Recommendedversion.

Notes

• 1 JRE 8 or higher is required for Connector/J 5.1 to connect to MySQL 5.6, 5.7,and 8.0 with SSL/TLS when using some cipher suites.

• 2 A customized JSSE provider might be required to use some later TLS versionsand cipher suites when connecting to MySQL servers. For example, becauseOracle's Java 8 is shipped with a JSSE implementation that only supports

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Connector/J Release Notes and Change History

TLSv1.2 and lower, you need a customized JSSE implementation to use TLSv1.3on Oracle's Java 8 platform.

• 3 If you are building Connector/J 5.1 from source code using the sourcedistribution, you must have both JDK 8.0 or higher AND JDK 5.0 installed. Itis also good to have JRE 6 for compiling Connector/J 5.1. See Section 3.4,“Installing from Source” for details.

This guide also covers earlier versions of Connector/J, with specific notes given where a setting applies toa specific version.

2.1 Connector/J Release Notes and Change History

For details of new features and bug fixes in each Connector/J release, see the MySQL Connector/J 5.1Release Notes.

2.2 Java Versions Supported

See Chapter 2, Connector/J Versions, and the MySQL and Java Versions They Require.

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Chapter 3 Connector/J Installation

Table of Contents3.1 Installing Connector/J from a Binary Distribution ............................................................................ 53.2 Installing the Driver and Configuring the CLASSPATH ..................................................................... 53.3 Upgrading from an Older Version .................................................................................................. 6

3.3.1 Upgrading to MySQL Connector/J 5.1.x .............................................................................. 73.3.2 JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer ................................ 73.3.3 Upgrading from MySQL Connector/J 3.0 to 3.1 ................................................................... 7

3.4 Installing from Source ................................................................................................................... 93.5 Testing Connector/J .................................................................................................................... 13

MySQL Connector/J is distributed as a .zip or .tar.gz archive, available for download from the Connector/J Download page. The archive contains the sources and the JAR archive named mysql-connector-java-version-bin.jar.

You can install the Connector/J package using either the binary or source distribution. The binarydistribution provides the easiest method for installation; the source distribution lets you customizeyour installation further. With either solution, you manually add the Connector/J location to your JavaCLASSPATH.

If you are upgrading from a previous version, read the upgrade information in Section 3.3, “Upgrading froman Older Version” before continuing.

Connector/J is also available as part of the Maven project. For more information and to download theConnector/J JAR files, see the Maven repository.

Important

You also need to install the Simple Logging Facade API to usethe logging capabilities provided by the default implementation oforg.slf4j.Logger.Slf4JLogger by Connector/J. That and other third-partylibraries are required for building Connector/J from source (see the section for moreinformation on the required libraries).

3.1 Installing Connector/J from a Binary DistributionFor the easiest method of installation, use the binary distribution of the Connector/J package. Extract theJAR archive from the tar/gzip or zip archive to a suitable location, then optionally make the informationabout the JAR archive available by changing your CLASSPATH (see Section 3.2, “Installing the Driver andConfiguring the CLASSPATH”).

Use the appropriate graphical or command-line utility to extract the distribution (for example, WinZip forthe .zip archive, and tar for the .tar.gz archive). Because there are potentially long file names in thedistribution, we use the GNU tar archive format. Use GNU tar (or an application that understands the GNUtar archive format) to unpack the .tar.gz variant of the distribution.

3.2 Installing the Driver and Configuring the CLASSPATHOnce you have extracted the distribution archive, you can install the driver by placing mysql-connector-java-version-bin.jar in your classpath, either by adding the full path to it to your CLASSPATHenvironment variable, or by directly specifying it with the command line switch -cp when starting the JVM.

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https://dev.mysql.com/downloads/connector/j/


https://search.maven.org/search?q=g:mysql%20AND%20a:mysql-connector-java

Upgrading from an Older Version

To use the driver with the JDBC DriverManager, use com.mysql.jdbc.Driver as the class thatimplements java.sql.Driver.

You can set the CLASSPATH environment variable under Unix, Linux, or macOS either locally for a userwithin their .profile, .login or other login file. You can also set it globally by editing the global /etc/profile file.

For example, add the Connector/J driver to your CLASSPATH using one of the following forms, dependingon your command shell:

# Bourne-compatible shell (sh, ksh, bash, zsh):$> export CLASSPATH=/path/mysql-connector-java-ver-bin.jar:$CLASSPATH

# C shell (csh, tcsh):$> setenv CLASSPATH /path/mysql-connector-java-ver-bin.jar:$CLASSPATH

For Windows platforms, you set the environment variable through the System Control Panel.

To use MySQL Connector/J with an application server such as GlassFish, Tomcat, or JBoss, readyour vendor's documentation for more information on how to configure third-party class libraries, asmost application servers ignore the CLASSPATH environment variable. For configuration examplesfor some J2EE application servers, see Chapter 7, Connection Pooling with Connector/J, Section 8.2,“Configuring Load Balancing with Connector/J”, and Section 8.4, “Advanced Load-balancing and FailoverConfiguration”. However, the authoritative source for JDBC connection pool configuration information foryour particular application server is the documentation for that application server.

If you are developing servlets or JSPs, and your application server is J2EE-compliant, you can put thedriver's .jar file in the WEB-INF/lib subdirectory of your webapp, as this is a standard location for thirdparty class libraries in J2EE web applications.

You can also use the MysqlDataSource or MysqlConnectionPoolDataSource classes in thecom.mysql.jdbc.jdbc2.optional package, if your J2EE application server supports or requiresthem. Starting with Connector/J 5.0.0, the javax.sql.XADataSource interface is implemented usingthe com.mysql.jdbc.jdbc2.optional.MysqlXADataSource class, which supports XA distributedtransactions when used in combination with MySQL server version 5.0 and later.

The various MysqlDataSource classes support the following parameters (through standard setmutators):

• user

• password

• serverName (see the previous section about failover hosts)

• databaseName

• port

3.3 Upgrading from an Older Version

This section has information for users who are upgrading from one version of Connector/J to another,or to a new version of the MySQL server that supports a more recent level of JDBC. A newer version ofConnector/J might include changes to support new features, improve existing functionality, or comply withnew standards.

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Upgrading to MySQL Connector/J 5.1.x

3.3.1 Upgrading to MySQL Connector/J 5.1.x

• In Connector/J 5.0.x and earlier, the alias for a table in a SELECT statement is returned when accessingthe result set metadata using ResultSetMetaData.getColumnName(). This behavior however isnot JDBC compliant, and in Connector/J 5.1, this behavior has been changed so that the original tablename, rather than the alias, is returned.

The JDBC-compliant behavior is designed to let API users reconstruct the DML statement based on themetadata within ResultSet and ResultSetMetaData.

You can get the alias for a column in a result set by callingResultSetMetaData.getColumnLabel(). To use the old noncompliant behavior withResultSetMetaData.getColumnName(), use the useOldAliasMetadataBehavior option andset the value to true.

In Connector/J 5.0.x, the default value of useOldAliasMetadataBehavior was true, but inConnector/J 5.1 this was changed to a default value of false.

3.3.2 JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer

• Using the UTF-8 Character Encoding - Prior to MySQL server version 4.1, the UTF-8 character encodingwas not supported by the server, however the JDBC driver could use it, allowing storage of multiplecharacter sets in latin1 tables on the server.

Starting with MySQL-4.1, this functionality is deprecated. If you have applications that rely on thisfunctionality, and can not upgrade them to use the official Unicode character support in MySQL serverversion 4.1 or newer, add the following property to your connection URL:

useOldUTF8Behavior=true

• Server-side Prepared Statements - Connector/J 3.1 will automatically detect and use server-sideprepared statements when they are available (MySQL server version 4.1.0 and newer). If yourapplication encounters issues with server-side prepared statements, you can revert to the older client-side emulated prepared statement code that is still presently used for MySQL servers older than 4.1.0with the following connection property:

useServerPrepStmts=false

3.3.3 Upgrading from MySQL Connector/J 3.0 to 3.1

Connector/J 3.1 is designed to be backward-compatible with Connector/J 3.0 as much as possible. Majorchanges are isolated to new functionality exposed in MySQL-4.1 and newer, which includes Unicodecharacter sets, server-side prepared statements, SQLState codes returned in error messages by theserver and various performance enhancements that can be enabled or disabled using configurationproperties.

• Unicode Character Sets: See the next section, as well as Character Sets, Collations, Unicode, forinformation on this MySQL feature. If you have something misconfigured, it will usually show up as anerror with a message similar to Illegal mix of collations.

• Server-side Prepared Statements: Connector/J 3.1 will automatically detect and use server-sideprepared statements when they are available (MySQL server version 4.1.0 and newer).

Starting with version 3.1.7, the driver scans SQL you are preparing using all variants ofConnection.prepareStatement() to determine if it is a supported type of statement to prepare onthe server side, and if it is not supported by the server, it instead prepares it as a client-side emulated

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Upgrading from MySQL Connector/J 3.0 to 3.1

prepared statement. You can disable this feature by passing emulateUnsupportedPstmts=false inyour JDBC URL.

If your application encounters issues with server-side prepared statements, you can revert to the olderclient-side emulated prepared statement code that is still presently used for MySQL servers older than4.1.0 with the connection property useServerPrepStmts=false.

• Datetimes with all-zero components (0000-00-00 ...): These values cannot be represented reliablyin Java. Connector/J 3.0.x always converted them to NULL when being read from a ResultSet.

Connector/J 3.1 throws an exception by default when these values are encountered, as this is the mostcorrect behavior according to the JDBC and SQL standards. This behavior can be modified using thezeroDateTimeBehavior configuration property. The permissible values are:

• exception (the default), which throws an SQLException with an SQLState of S1009.

• convertToNull, which returns NULL instead of the date.

• round, which rounds the date to the nearest closest value which is 0001-01-01.

Starting with Connector/J 3.1.7, ResultSet.getString() can be decoupled from this behavior usingnoDatetimeStringSync=true (the default value is false) so that you can retrieve the unalteredall-zero value as a String. Note that this also precludes using any time zone conversions, therefore thedriver will not allow you to enable noDatetimeStringSync and useTimezone at the same time.

• New SQLState Codes: Connector/J 3.1 uses SQL:1999 SQLState codes returned by the MySQL server(if supported), which are different from the legacy X/Open state codes that Connector/J 3.0 uses. Ifconnected to a MySQL server older than MySQL-4.1.0 (the oldest version to return SQLStates as partof the error code), the driver will use a built-in mapping. You can revert to the old mapping by using theconfiguration property useSqlStateCodes=false.

• ResultSet.getString(): Calling ResultSet.getString() on a BLOB column will now return theaddress of the byte[] array that represents it, instead of a String representation of the BLOB. BLOBvalues have no character set, so they cannot be converted to java.lang.Strings without data loss orcorruption.

To store strings in MySQL with LOB behavior, use one of the TEXT types, which the driver will treat as ajava.sql.Clob.

• Debug builds: Starting with Connector/J 3.1.8 a debug build of the driver in a file named mysql-connector-java-version-bin-g.jar is shipped alongside the normal binary jar file that is namedmysql-connector-java-version-bin.jar.

Starting with Connector/J 3.1.9, we do not ship the .class files unbundled, they are only available inthe JAR archives that ship with the driver.

Do not use the debug build of the driver unless instructed to do so when reporting a problem or bug, asit is not designed to be run in production environments, and will have adverse performance impact whenused. The debug binary also depends on the Aspect/J runtime library, which is located in the src/lib/aspectjrt.jar file that comes with the Connector/J distribution.

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Installing from Source

3.4 Installing from Source

Caution

To just get MySQL Connector/J up and running on your system, install Connector/J using a standard binary release distribution. Instructions in this section is only forusers who, for various reasons, want to compile Connector/J from source.

The requirements and steps for installing from source Connector/J 5.1.37 or later, 5.1.34 to 5.1.36, and5.1.33 or earlier are different; check the section below that is relevant for the version you want.

Installing Connector/J 5.1.37 or later from source. To install MySQL Connector/J from its source treeon GitHub, you need to have the following software on your system:

• A Git client, to check out the sources from our GitHub repository (available from http://git-scm.com/downloads).

• Apache Ant version 1.8.2 or newer (available from http://ant.apache.org/).

• JDK 1.8.x AND JDK 1.5.x.

• JRE 1.6.x (optional)

• The following third-party libraries:

• JUnit 4.12 (junit-4.12.jar, available from https://github.com/junit-team/junit/wiki/Download-and-Install).

• C3P0 0.9.1 or newer (both c3p0-0.9.1.x.jar and c3p0-0.9.1.x.src.zip, available fromhttps://sourceforge.net/projects/c3p0/).

• JBoss common JDBC wrapper 3.2.3 or newer (jboss-common-jdbc-wrapper-3.2.3.jar,available from, for example, the Maven Central Repository at http://central.maven.org/maven2/jboss/jboss-common-jdbc-wrapper/).

• Simple Logging Facade API 1.6.1 or newer (slf4j-api-1.6.1.jar, available from https://www.slf4j.org/download.html).

• The required .jar files from the Hibernate ORM 4.1 or 4.2 Final release bundle, which is available athttp://sourceforge.net/projects/hibernate/files/hibernate4/.

To check out and compile MySQL Connector/J, follow these steps:

1. Check out the code from the source code repository for MySQL Connector/J located on GitHub athttps://github.com/mysql/mysql-connector-j; for the latest release of the Connector/J 5.1 series, use thefollowing command:

$> git clone https://github.com/mysql/mysql-connector-j.git

To check out a release other than the latest one, use the --branch option to specify the revision tagfor it:

$> git clone --branch 5.1 https://github.com/mysql/mysql-connector-j.git

Under the current directory, the commands create a mysql-connector-j subdirectory , whichcontains the code you want.

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https://www.slf4j.org/download.html


http://sourceforge.net/projects/hibernate/files/hibernate4/

https://github.com/mysql/mysql-connector-j


2. Make sure that you have both JDK 1.8.x AND JDK 1.5.x installed. You need both JDKs becausebesides supporting JDBC from 4.0 to 4.2, Connector/J 5.1 also supports JDBC 3.0, which is an olderversion and requires the older JDK 1.5.x.

3. Consider also having JRE 1.6.x installed. This is optional: if JRE 1.6.x is not available or not suppliedto Ant with the property com.mysql.jdbc.java6.rtjar, the Java 8 bootstrap classes will be used.A warning will be returned, saying that the bootstrap class path was not set with the option to compilesources written for Java 6.

4. Place the required junit.jar file in a separate directory—for example, /home/username/ant-extralibs.

5. In the same directory for extra libraries described in the last step, create a directory namedhibernate4, and put under it all the .jar files you can find under the /lib/required/ folder in theHibernate ORM 4 Final release bundle.

6. Change your current working directory to the mysql-connector-j directory created in step 1 above.

7. In the directory, create a file named build.properties to indicate to Ant the locations of the rootdirectories for your JDK 1.8.x and JDK 1.5.x installations, the location of the rt.jar of your JRE 1.6.x(optional), and the location of the extra libraries. The file should contain the following property settings,with the “path_to_*” parts replaced by the appropriate filepaths:

com.mysql.jdbc.jdk8=path_to_jdk_1.8com.mysql.jdbc.jdk5=path_to_jdk_1.5com.mysql.jdbc.java6.rtjar=path_to_rt.jar_under_jre_1.6/rt.jarcom.mysql.jdbc.extra.libs=path_to_folder_for_extra_libraries

Alternatively, you can set the values of those properties through the Ant -D options.

8. Issue the following command to compile the driver and create a .jar file for Connector/J:

$> ant dist

This creates a build directory in the current directory, where all the build output goes. A directoryis created under the build directory, whose name includes the version number of the release youare building. That directory contains the sources, the compiled .class files, and a .jar file fordeployment. For more information and other possible targets, including those that create a fullypackaged distribution, issue the following command:

$> ant -projecthelp

9. Install the newly created .jar file for the JDBC driver as you would install a binary .jar file youdownload from MySQL by following the instructions given in Section 3.2, “Installing the Driver andConfiguring the CLASSPATH”.

Note that a package containing both the binary and source code for Connector/J 5.1 can also bedownloaded from the Connector/J Download page.

Installing Connector/J 5.1.34 to 5.1.36 from source. To install MySQL Connector/J 5.1.34 to 5.1.36from the Connector/J source tree on GitHub, make sure that you have the following software on yoursystem:

• A Git client, to check out the sources from our GitHub repository (available from http://git-scm.com/downloads).

• Apache Ant version 1.8.2 or newer (available from http://ant.apache.org/).

• JDK 1.6.x AND JDK 1.5.x.

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• JUnit libraries (available from https://github.com/junit-team/junit/wiki/Download-and-Install).


To check out and compile MySQL Connector/J, follow these steps:

1. Check out the code from the source code repository for MySQL Connector/J located on GitHub athttps://github.com/mysql/mysql-connector-j, using the --branch option to specify the revision tag forrelease 5.1.xx:

$> git clone --branch 5.1.xx https://github.com/mysql/mysql-connector-j.git


2. Make sure that you have both JDK 1.6.x AND JDK 1.5.x installed. You need both JDKs becauseConnector/J 5.1 supports both JDBC 3.0 (which has existed prior to JDK 1.6.x) and JDBC 4.0.

3. Place the required junit.jar file in a separate directory—for example, /home/username/ant-extralibs.



6. In the directory, create a file named build.properties to indicate to Ant the locations of the rootdirectories for your JDK 1.5.x and JDK 1.6.x installations, as well as the location of the extra libraries.The file should contain the following property settings, with the “path_to_*” parts replaced by theappropriate filepaths:

com.mysql.jdbc.jdk5=path_to_jdk_1.5com.mysql.jdbc.jdk6=path_to_jdk_1.6com.mysql.jdbc.extra.libs=path_to_folder_for_extra_libraries



$> ant dist


$> ant -projecthelp


Installing Connector/J 5.1.33 or earlier from the source tree. To install MySQL Connector/J 5.1.33or earlier from the Connector/J source tree on GitHub, make sure that you have the following software onyour system:

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• A Git client, to check out the source code from our GitHub repository (available from http://git-scm.com/downloads).

• Apache Ant version 1.7 or newer (available from http://ant.apache.org/).

• JDK 1.6.x AND JDK 1.5.x. Refer to Section 2.2, “Java Versions Supported” for the version of Java youneed to build or run any Connector/J release.

• The Ant Contrib (version 1.03b is available from http://sourceforge.net/projects/ant-contrib/files/ant-contrib/1.0b3/) and JUnit (available from https://github.com/junit-team/junit/wiki/Download-and-Install)libraries.


To check out and compile a specific branch of MySQL Connector/J, follow these steps:

1. Check out the code from the source code repository for MySQL Connector/J located on GitHub athttps://github.com/mysql/mysql-connector-j, using the --branch option to specify the revision tag forrelease 5.1.xx:

$> git clone --branch 5.1.xx https://github.com/mysql/mysql-connector-j.git


2. To build Connector/J 5.1, make sure that you have both JDK 1.6.x AND JDK 1.5.x installed. You needboth JDKs because Connector/J 5.1 supports both JDBC 3.0 (which has existed prior to JDK 1.6.x) andJDBC 4.0. Set your JAVA_HOME environment variable to the path to the JDK 1.5.x installation.

3. Place the required ant-contrib.jar file (in exactly that name, without the version number in it;rename the jar file if needed) and junit.jar file in a separate directory—for example, /home/username/ant-extralibs.



6. In the directory, create a file named build.properties to indicate to Ant the locations of the Javacand rt.jar of your JDK 1.6.x, as well as the location of the extra libraries. The file should contain thefollowing property settings, with the “path_to_*” parts replaced by the appropriate filepaths:

com.mysql.jdbc.java6.javac=path_to_javac_1.6/javaccom.mysql.jdbc.java6.rtjar=path_to_rt.jar_under_jdk_1.6/rt.jarcom.mysql.jdbc.extra.libs=path_to_folder_for_extra_libraries



$> ant dist


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http://sourceforge.net/projects/ant-contrib/files/ant-contrib/1.0b3/

http://sourceforge.net/projects/ant-contrib/files/ant-contrib/1.0b3/




Testing Connector/J

$> ant -projecthelp


3.5 Testing Connector/JThe Connector/J source code repository or packages that are shipped with source code include anextensive test suite, containing test cases that can be executed independently. The test cases are dividedinto the following categories:

• Functional or unit tests: Classes from the package testsuite.simple. Include test code for the mainfeatures of the Connector/J.

• Performance tests: Classes from the package testsuite.perf. Include test code to makemeasurements for the performance of Connector/J.

• Regression tests: Classes from the package testsuite.regression. Includes code for testing bugand regression fixes.

The bundled Ant build file contains targets like test and test-multijvm, which can facilitate theprocess of running the Connector/J tests; see the target descriptions in the build file for details. Besidesthe requirements for building Connector/J from the source code described in Section 3.4, “Installing fromSource”, a number of the tests also require the File System Service Provider 1.2 for the Java Naming andDirectory Interface (JNDI), available at http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-java-plat-419418.html)—place the jar files downloaded from there into the libdirectory or in the directory pointed to by the property com.mysql.jdbc.extra.libs.

To run the test using Ant, in addition to the properties required for Section 3.4, “Installing from Source”, youmust set the following properties in the build.properties file or through the Ant -D options:

• com.mysql.jdbc.testsuite.url: it specifies the JDBC URL for connection to a MySQL test server;see Section 5.3, “Configuration Properties for Connector/J”.

• com.mysql.jdbc.testsuite.jvm: the JVM to be used for the tests. If the property is set,the specified JVM will be used for all test cases except if it points to a Java 5 directory, in whichcase any test cases for JDBC 4.0 and later are run with the JVM supplied with the propertycom.mysql.jdbc.jdk8 (for 5.1.36 and earlier, supplied with the property com.mysql.jdbc.jdk6). Ifthe property is not set, the JVM supplied with com.mysql.jdbc.jdk5 will be used to run test cases forJDBC 3.0 and the one supplied with com.mysql.jdbc.jdk8 (for 5.1.36 and earlier, supplied with theproperty com.mysql.jdbc.jdk6) will be used to run test cases for JDBC 4.0 and later.

After setting these parameters, run the tests with Ant in the following ways:

• Building the test target with ant test runs all test cases by default on a single server instance. Ifyou want to run a particular test case, put the test's fully qualified class names in the test variable; forexample:

shell > ant -Dtest=testsuite.simple.StringUtilsTest test

You can also run individual tests in a test case by specifying the names of the corresponding methods inthe methods variable, separating multiple methods by commas; for example:

shell > ant -Dtest=testsuite.simple.StringUtilsTest -Dmethods=testIndexOfIgnoreCase,testGetBytes test

• Building the test-multijvm target with ant test-multijvm runs all the test cases using multipleJVMs of different versions on multiple server instances. For example, if you want to run the tests using a

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http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-java-plat-419418.html

http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-java-plat-419418.html

Testing Connector/J

Java 7 and a Java 8 JVM on three server instances with different configurations, you will need to use thefollowing properties:

com.mysql.jdbc.testsuite.jvm.1=path_to_Java_7com.mysql.jdbc.testsuite.jvm.2=path_to_Java_8com.mysql.jdbc.testsuite.url.1=URL_to_1st_servercom.mysql.jdbc.testsuite.url.2=URL_to_2nd_servercom.mysql.jdbc.testsuite.url.3=URL_to_3rd_server

Unlike the target test, the target test-multijvm only recognizes the propertiescom.mysql.jdbc.testsuite.jvm.N and com.mysql.jdbc.testsuite.url.N, where N is anumeric suffice; the same properties without the suffices are ignored by test-multijvm. As with thetarget test, if any of the com.mysql.jdbc.testsuite.jvm.N settings points to Java 5, then Antrelies on the property com.mysql.jdbc.jdk8 to run the tests specific to JDBC 4.0 and later.

You can choose to run individual test cases or specific tests by using the test or methods property, asexplained in the last bullet for the target test. Each test is run once per possible combination of JVMsand server instances (that is, 6 times in total for in this example).

When a test for a certain JVM-server combination has failed, test-multijvm does not throw an error,but moves on to the next combination, until all tests for all combinations are finished.

While the test results are partially reported by the console, complete reports in HTML and XML formats areprovided:

• For results of test: view the HTML report by opening build/junit/unitregress/report/index.html. XML version of the reports are located in the folder build/junit/unitregress.

• For results of test-multijvm: view the HTML report for each JVM-server combination by openingbuild/junit/MySQLN.server_version/operating_system_version/jvm-version/unitregress/report/index.html. XML version of the reports are located in the folder build/junit/MySQLN.server_version/operating_system_version/jvm-version/unitregress.

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Chapter 4 Connector/J ExamplesExamples of using Connector/J are located throughout this document. This section provides a summaryand links to these examples.

• Example 6.1, “Connector/J: Obtaining a connection from the DriverManager”

• Example 6.2, “Connector/J: Using java.sql.Statement to execute a SELECT query”

• Example 6.3, “Connector/J: Calling Stored Procedures”

• Example 6.4, “Connector/J: Using Connection.prepareCall()”

• Example 6.5, “Connector/J: Registering output parameters”

• Example 6.6, “Connector/J: Setting CallableStatement input parameters”

• Example 6.7, “Connector/J: Retrieving results and output parameter values”

• Example 6.8, “Connector/J: Retrieving AUTO_INCREMENT column values usingStatement.getGeneratedKeys()”

• Example 6.9, “Connector/J: Retrieving AUTO_INCREMENT column values using SELECTLAST_INSERT_ID()”

• Example 6.10, “Connector/J: Retrieving AUTO_INCREMENT column values in UpdatableResultSets”

• Example 7.1, “Connector/J: Using a connection pool with a J2EE application server”

• Example 15.1, “Connector/J: Example of transaction with retry logic”

15

Chapter 5 Connector/J (JDBC) Reference

Table of Contents5.1 Driver/Datasource Class Name ................................................................................................... 175.2 Connection URL Syntax .............................................................................................................. 175.3 Configuration Properties for Connector/J ...................................................................................... 19

5.3.1 Connection/Authentication ................................................................................................ 205.3.2 Networking ...................................................................................................................... 225.3.3 High Availability and Clustering ........................................................................................ 235.3.4 Security ........................................................................................................................... 265.3.5 Performance Extensions .................................................................................................. 295.3.6 Debugging/Profiling .......................................................................................................... 355.3.7 Miscellaneous .................................................................................................................. 395.3.8 The useConfigs Option and the Configuration Property Files .............................................. 53

5.4 JDBC API Implementation Notes ................................................................................................. 545.5 Java, JDBC and MySQL Types ................................................................................................... 575.6 Using Character Sets and Unicode ............................................................................................. 605.7 Connecting Securely Using SSL .................................................................................................. 615.8 Connecting Using Unix Domain Sockets ...................................................................................... 655.9 Connecting Using Named Pipes .................................................................................................. 655.10 Connecting Using PAM Authentication ....................................................................................... 665.11 Source/Replica Using Replication with ReplicationConnection ..................................................... 675.12 Mapping MySQL Error Numbers to JDBC SQLState Codes ........................................................ 67

This section of the manual contains reference material for MySQL Connector/J.

5.1 Driver/Datasource Class NameThe name of the class that implements java.sql.Driver in MySQL Connector/J iscom.mysql.jdbc.Driver.

The org.gjt.mm.mysql.Driver class name is also usable for backward compatibility with MM.MySQL,the predecessor of Connector/J. Use this class name when registering the driver, or when configuring asoftware to use MySQL Connector/J.

5.2 Connection URL SyntaxThis section explains the syntax of the URLs for connecting to MySQL.

This is the generic format of the connection URL:

protocol//[hosts][/database][?properties]

The URL consists of the following parts:

Important

Any reserved characters for URLs (for example, /, :, @, (, ), [, ], &, #, =, ?, andspace) that appear in any part of the connection URL must be percent encoded.

protocol

There are three possible protocols for a connection:

17

hosts

• jdbc:mysql: is for ordinary and basic failover connections.

• jdbc:mysql:loadbalance: is for configuring load balancing. See Section 8.2, “Configuring LoadBalancing with Connector/J” for details.

• jdbc:mysql:replication: is for configuring a replication setup. See Section 8.3, “ConfiguringSource/Replica Replication with Connector/J” for details.

hosts

Depending on the situation, the hosts part may consist simply of a host name, or it can be a complexstructure consisting of various elements like multiple host names, port numbers, host-specific properties,and user credentials.

• Single host:

• Single-host connections without adding host-specific properties:

• The hosts part is written in the format of host:port. This is an example of a simple single-hostconnection URL:

jdbc:mysql://host1:33060/sakila

• When host is not specified, the default value of localhost is used.

• port is a standard port number, i.e., an integer between 1 and 65535. The default port number foran ordinary MySQL connection is 3306. If port is not specified, the default value is used.

• Single-host connections adding host-specific properties:

• The host is defined as a succession of key=value pairs. Keys are used to identify the host, theport, as well as any host-specific properties, and they are preceded by “address=”:

address=(host=host_or_ip)(port=port)(key1=value1)(key2=value2)...(keyN=valueN)

Here is a sample URL:

jdbc:mysql://address=(host=myhost)(port=1111)(key1=value1)/db

This is the mandatory format for iPv6 addresses, but it also supports the iPv4 addresses.

• The host and the port are identified by the keys host and port. The description of the defaultvalues of host and port in Single host without host-specific properties [18] above also applieshere.

• Other keys that can be added include user, password, protocol, and so on. They overridethe global values set in the properties part of the URL. Limit the overrides to user, password,network timeouts, and statement and metadata cache sizes; the effects of other per-host overridesare not defined.

• key is case-sensitive. Two keys differing in case only are considered conflicting, and there are noguarantees on which one will be used.

• Multiple hosts

• Specify multiple hosts by listing them in a comma-separated list:

host1,host2,...,hostN

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database

Each host can be specified in any of the two ways described in Single host [18] above. Here aresome examples:

jdbc:mysql://myhost1:1111,myhost2:2222/dbjdbc:mysql://address=(host=myhost1)(port=1111)(key1=value1),address=(host=myhost2)(port=2222)(key2=value2)/dbjdbc:mysql://myhost1:1111,address=(host=myhost2)(port=2222)(key2=value2)/db

• User credentials

User credentials can be set outside of the connection URL—for example, as arguments when gettinga connection from the java.sql.DriverManager (see Section 5.3, “Configuration Properties forConnector/J” for details). When set with the connection URL, use the keys user and password tospecify credentials for each host:

(user=sandy)(password=mypass)

For example:

jdbc:mysql://address=(host=myhost1)(port=1111)(user=sandy)(password=secret),address=(host=myhost2)(port=2222)(user=finn)(password=secret)/db

When multiple user credentials are specified, the one to the left takes precedence—that is, going fromleft to right in the connection string, the first one found that is applicable to a host is the one that is used.

database

The default database or catalog to open. If the database is not specified, the connection is made with nodefault database. In this case, either call the setCatalog() method on the Connection instance, orspecify table names using the database name (that is, SELECT dbname.tablename.colname FROMdbname.tablename...) in your SQL statements. Opening a connection without specifying the databaseto use is, in general, only useful when building tools that work with multiple databases, such as GUIdatabase managers.

Note

Always use the Connection.setCatalog() method to specify the desireddatabase in JDBC applications, rather than the USE database statement.

properties

A succession of global properties applying to all hosts, preceded by “?” and written as key=value pairsseparated by the symbol “&.” Here are some examples:

jdbc:mysql://(host=myhost1,port=1111),(host=myhost2,port=2222)/db?key1=value1&key2=value2&key3=value3

The following are true for the key-value pairs:

• key and value are just strings. Proper type conversion and validation are performed internally inConnector/J.

• key is case-sensitive. Two keys differing in case only are considered conflicting, and it is uncertainwhich one will be used.

• Any host-specific values specified with key-value pairs as explained in Single host with host-specificproperties [18] and Multiple hosts [18] above override the global values set here.

5.3 Configuration Properties for Connector/J

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Connection/Authentication

Configuration properties define how Connector/J will make a connection to a MySQL server. Unlessotherwise noted, properties can be set for a DataSource object or for a Connection object.

Configuration properties can be set in one of the following ways:

• Using the set*() methods on MySQL implementations of java.sql.DataSource (which is thepreferred method when using implementations of java.sql.DataSource):

• com.mysql.jdbc.jdbc2.optional.MysqlDataSource

• com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource

• As a key-value pair in the java.util.Properties instance passed toDriverManager.getConnection() or Driver.connect()

• As a JDBC URL parameter in the URL given to java.sql.DriverManager.getConnection(),java.sql.Driver.connect() or the MySQL implementations of the javax.sql.DataSourcesetURL() method. If you specify a configuration property in the URL without providing a value forit, nothing will be set; for example, adding useServerPrepStmts alone to the URL does not makeConnector/J use server-side prepared statements; you need to add useServerPrepStmts=true.

Note

If the mechanism you use to configure a JDBC URL is XML-based, use the XMLcharacter literal & to separate configuration parameters, as the ampersandis a reserved character for XML.

The configuration properties are categorized into the following sections, in which details for each propertyare given.

5.3.1 Connection/Authentication

• user

The user to connect as

Since Version all versions

• password

The password to use when connecting


• socketFactory

The name of the class that the driver should use for creating socket connections to the server. This classmust implement the interface 'com.mysql.jdbc.SocketFactory' and have public no-args constructor.

Default Value com.mysql.jdbc.StandardSocketFactory

Since Version 3.0.3

• connectTimeout

Timeout for socket connect (in milliseconds), with 0 being no timeout. Only works on JDK-1.4 or newer.Defaults to '0'.

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Connection/Authentication

Default Value 0

Since Version 3.0.1

• socketTimeout

Timeout (in milliseconds) on network socket operations (0, the default means no timeout).

Default Value 0

Since Version 3.0.1

• connectionLifecycleInterceptors

A comma-delimited list of classes that implement "com.mysql.jdbc.ConnectionLifecycleInterceptor" thatshould notified of connection lifecycle events (creation, destruction, commit, rollback, setCatalog andsetAutoCommit) and potentially alter the execution of these commands. ConnectionLifecycleInterceptorsare "stackable", more than one interceptor may be specified via the configuration property as a comma-delimited list, with the interceptors executed in order from left to right.

Since Version 5.1.4

• useConfigs

Load the comma-delimited list of configuration properties before parsing the URL or applying user-specified properties. These configurations are explained in the 'Configurations' of the documentation.

Since Version 3.1.5

• authenticationPlugins

Comma-delimited list of classes that implement com.mysql.jdbc.AuthenticationPlugin and which will beused for authentication unless disabled by "disabledAuthenticationPlugins" property.

Since Version 5.1.19

• defaultAuthenticationPlugin

Name of a class implementing com.mysql.jdbc.AuthenticationPlugin which will be used asthe default authentication plugin (see below). It is an error to use a class which is not listed in"authenticationPlugins" nor it is one of the built-in plugins. It is an error to set as default a plugin whichwas disabled with "disabledAuthenticationPlugins" property. It is an error to set this value to null or theempty string (i.e. there must be at least a valid default authentication plugin specified for the connection,meeting all constraints listed above).

Default Value com.mysql.jdbc.authentication.MysqlNativePasswordPlugin


• disabledAuthenticationPlugins

Comma-delimited list of classes implementing com.mysql.jdbc.AuthenticationPlugin or mechanisms,i.e. "mysql_native_password". The authentication plugins or mechanisms listed will not be used forauthentication which will fail if it requires one of them. It is an error to disable the default authenticationplugin (either the one named by "defaultAuthenticationPlugin" property or the hard-coded one if"defaultAuthenticationPlugin" property is not set).

21

Networking


• disconnectOnExpiredPasswords

If "disconnectOnExpiredPasswords" is set to "false" and password is expired then server enters"sandbox" mode and sends ERR(08001, ER_MUST_CHANGE_PASSWORD) for all commands that arenot needed to set a new password until a new password is set.

Default Value true


• interactiveClient

Set the CLIENT_INTERACTIVE flag, which tells MySQL to timeout connections based onINTERACTIVE_TIMEOUT instead of WAIT_TIMEOUT

Default Value false

Since Version 3.1.0

• localSocketAddress

Hostname or IP address given to explicitly configure the interface that the driver will bind the client sideof the TCP/IP connection to when connecting.

Since Version 5.0.5

• propertiesTransform

An implementation of com.mysql.jdbc.ConnectionPropertiesTransform that the driver will use to modifyURL properties passed to the driver before attempting a connection

Since Version 3.1.4

• useCompression

Use zlib compression when communicating with the server (true/false)? Defaults to 'false'.

Default Value false


5.3.2 Networking

• socksProxyHost

Name or IP address of SOCKS host to connect through.


• socksProxyPort

Port of SOCKS server.

Default Value 1080

22

High Availability and Clustering


• maxAllowedPacket

Maximum allowed packet size to send to server. If not set, the value of system variable'max_allowed_packet' will be used to initialize this upon connecting. This value will not take effect if setlarger than the value of 'max_allowed_packet'. Also, due to an internal dependency with the property'blobSendChunkSize', this setting has a minimum value of '8203' if 'useServerPrepStmts' is set to 'true'.

Default Value -1

Since Version 5.1.8

• tcpKeepAlive

If connecting using TCP/IP, should the driver set SO_KEEPALIVE?

Default Value true

Since Version 5.0.7

• tcpNoDelay

If connecting using TCP/IP, should the driver set SO_TCP_NODELAY (disabling the Nagle Algorithm)?

Default Value true

Since Version 5.0.7

• tcpRcvBuf

If connecting using TCP/IP, should the driver set SO_RCV_BUF to the given value? The default value of'0', means use the platform default value for this property)

Default Value 0

Since Version 5.0.7

• tcpSndBuf

If connecting using TCP/IP, should the driver set SO_SND_BUF to the given value? The default value of'0', means use the platform default value for this property)

Default Value 0

Since Version 5.0.7

• tcpTrafficClass

If connecting using TCP/IP, should the driver set traffic class or type-of-service fields ?See thedocumentation for java.net.Socket.setTrafficClass() for more information.

Default Value 0

Since Version 5.0.7

5.3.3 High Availability and Clustering

• autoReconnect

23


Should the driver try to re-establish stale and/or dead connections? If enabled the driver will throw anexception for a queries issued on a stale or dead connection, which belong to the current transaction,but will attempt reconnect before the next query issued on the connection in a new transaction. Theuse of this feature is not recommended, because it has side effects related to session state and dataconsistency when applications don't handle SQLExceptions properly, and is only designed to be usedwhen you are unable to configure your application to handle SQLExceptions resulting from dead andstale connections properly. Alternatively, as a last option, investigate setting the MySQL server variable"wait_timeout" to a high value, rather than the default of 8 hours.

Default Value false

Since Version 1.1

• autoReconnectForPools

Use a reconnection strategy appropriate for connection pools (defaults to 'false')

Default Value false

Since Version 3.1.3

• failOverReadOnly

When failing over in autoReconnect mode, should the connection be set to 'read-only'?

Default Value true


• maxReconnects

Maximum number of reconnects to attempt if autoReconnect is true, default is '3'.

Default Value 3

Since Version 1.1

• reconnectAtTxEnd

If autoReconnect is set to true, should the driver attempt reconnections at the end of every transaction?

Default Value false


• retriesAllDown

When using loadbalancing or failover, the number of times the driver should cycle through availablehosts, attempting to connect. Between cycles, the driver will pause for 250ms if no servers are available.

Default Value 120

Since Version 5.1.6

• initialTimeout

If autoReconnect is enabled, the initial time to wait between re-connect attempts (in seconds, defaults to'2').

24


Default Value 2

Since Version 1.1

• roundRobinLoadBalance

When autoReconnect is enabled, and failoverReadonly is false, should we pick hosts to connect to on around-robin basis?

Default Value false

Since Version 3.1.2

• queriesBeforeRetryMaster

Number of queries to issue before falling back to the primary host when failed over (whenusing multi-host failover). Whichever condition is met first, 'queriesBeforeRetryMaster' or'secondsBeforeRetryMaster' will cause an attempt to be made to reconnect to the primary host. Settingboth properties to 0 disables the automatic fall back to the primary host at transaction boundaries.Defaults to 50.

Default Value 50

Since Version 3.0.2

• secondsBeforeRetryMaster

How long should the driver wait, when failed over, before attempting to reconnect to the primary host?Whichever condition is met first, 'queriesBeforeRetryMaster' or 'secondsBeforeRetryMaster' will causean attempt to be made to reconnect to the source. Setting both properties to 0 disables the automatic fallback to the primary host at transaction boundaries. Time in seconds, defaults to 30

Default Value 30

Since Version 3.0.2

• allowMasterDownConnections

By default, a replication-aware connection will fail to connect when configured source hosts are allunavailable at initial connection. Setting this property to 'true' allows to establish the initial connection, byfailing over to the replica servers, in read-only state. It won't prevent subsequent failures when switchingback to the source hosts i.e. by setting the replication connection to read/write state.

Default Value false


• allowSlaveDownConnections

By default, a replication-aware connection will fail to connect when configured replica hosts are allunavailable at initial connection. Setting this property to 'true' allows to establish the initial connection.It won't prevent failures when switching to replicas i.e. by setting the replication connection to read-onlystate. The property 'readFromMasterWhenNoSlaves' should be used for this purpose.

Default Value false


Security

• readFromMasterWhenNoSlaves

Replication-aware connections distribute load by using the source hosts when in read/write state and byusing the replica hosts when in read-only state. If, when setting the connection to read-only state, noneof the replica hosts are available, an SQLExeception is thrown back. Setting this property to 'true' allowsto fail over to the source hosts, while setting the connection state to read-only, when no replica hosts areavailable at switch instant.

Default Value false


• replicationEnableJMX

Enables JMX-based management of load-balanced connection groups, including live addition/removal ofhosts from load-balancing pool.

Default Value false


• selfDestructOnPingMaxOperations

If set to a non-zero value, the driver will report close the connection and report failure whenConnection.ping() or Connection.isValid(int) is called if the connection's count of commands sent to theserver exceeds this value.

Default Value 0

Since Version 5.1.6

• selfDestructOnPingSecondsLifetime

If set to a non-zero value, the driver will close the connection and report failure when Connection.ping()or Connection.isValid(int) is called if the connection's lifetime exceeds this value (in milliseconds).

Default Value 0

Since Version 5.1.6

• replicationConnectionGroup

Logical group of replication connections within a classloader, used to manage different groupsindependently. If not specified, live management of replication connections is disabled.


• resourceId

A globally unique name that identifies the resource that this datasource or connection is connected to,used for XAResource.isSameRM() when the driver can't determine this value based on hostnames usedin the URL

Since Version 5.0.1

5.3.4 Security

• allowMultiQueries

26

Security

Allow the use of ';' to delimit multiple queries during one statement (true/false), defaults to'false', and does not affect the addBatch() and executeBatch() methods, which instead rely onrewriteBatchedStatements.

Default Value false

Since Version 3.1.1

• useSSL

Use SSL when communicating with the server (true/false), default is 'true' when connecting to MySQL5.5.45+, 5.6.26+, or 5.7.6+, otherwise default is 'false'

Default Value false

Since Version 3.0.2

• requireSSL

Require server support of SSL connection if useSSL=true? (defaults to 'false').

Default Value false

Since Version 3.1.0

• verifyServerCertificate

If "useSSL" is set to "true", should the driver verify the server's certificate? When using this feature,the keystore parameters should be specified by the "clientCertificateKeyStore*" properties, ratherthan system properties. Default is 'false' when connecting to MySQL 5.5.45+, 5.6.26+, or 5.7.6+ and"useSSL" was not explicitly set to "true". Otherwise default is 'true'

Default Value true

Since Version 5.1.6

• clientCertificateKeyStoreUrl

URL to the client certificate KeyStore (if not specified, use defaults)

Since Version 5.1.0

• clientCertificateKeyStoreType

KeyStore type for client certificates (NULL or empty means use the default, which is "JKS". Standardkeystore types supported by the JVM are "JKS" and "PKCS12", your environment may have moreavailable depending on what security products are installed and available to the JVM.

Default Value JKS

Since Version 5.1.0

• clientCertificateKeyStorePassword

Password for the client certificates KeyStore

Since Version 5.1.0

27

Security

• trustCertificateKeyStoreUrl

URL to the trusted root certificate KeyStore (if not specified, use defaults)

Since Version 5.1.0

• trustCertificateKeyStoreType

KeyStore type for trusted root certificates (NULL or empty means use the default, which is "JKS".Standard keystore types supported by the JVM are "JKS" and "PKCS12", your environment may havemore available depending on what security products are installed and available to the JVM.

Default Value JKS

Since Version 5.1.0

• trustCertificateKeyStorePassword

Password for the trusted root certificates KeyStore

Since Version 5.1.0

• enabledSSLCipherSuites

If "useSSL" is set to "true", overrides the cipher suites enabled for use on the underlying SSL sockets.This may be required when using external JSSE providers or to specify cipher suites compatible withboth MySQL server and used JVM.


• enabledTLSProtocols

If "useSSL" is set to "true", overrides the TLS protocols enabled for use on the underlying SSL sockets.This may be used to restrict connections to specific TLS versions.


• allowLoadLocalInfile

Should the driver allow use of 'LOAD DATA LOCAL INFILE...'?

Default Value false

Since Version 3.0.3

• allowUrlInLocalInfile

Should the driver allow URLs in 'LOAD DATA LOCAL INFILE' statements?

Default Value false


Performance Extensions

• allowPublicKeyRetrieval

Allows special handshake roundtrip to get server RSA public key directly from server.

Default Value false


• paranoid

Take measures to prevent exposure sensitive information in error messages and clear data structuresholding sensitive data when possible? (defaults to 'false')

Default Value false

Since Version 3.0.1

• passwordCharacterEncoding

What character encoding is used for passwords? Leaving this set to the default value (null), usesthe value set in "characterEncoding" if there is one, otherwise uses UTF-8 as default encoding. If thepassword contains non-ASCII characters, the password encoding must match what server encoding wasset to when the password was created. For passwords in other character encodings, the encoding willhave to be specified with this property (or with "characterEncoding"), as it's not possible for the driver toauto-detect this.

Since Version 5.1.7

• serverRSAPublicKeyFile

File path to the server RSA public key file for sha256_password authentication. If not specified, thepublic key will be retrieved from the server.


5.3.5 Performance Extensions

• callableStmtCacheSize

If 'cacheCallableStmts' is enabled, how many callable statements should be cached?

Default Value 100

Since Version 3.1.2

• metadataCacheSize

The number of queries to cache ResultSetMetadata for if cacheResultSetMetaData is set to'true' (default 50)

Default Value 50

Since Version 3.1.1

• useLocalSessionState

Should the driver refer to the internal values of autocommit and transaction isolation that are setby Connection.setAutoCommit() and Connection.setTransactionIsolation() and transaction state as

29


maintained by the protocol, rather than querying the database or blindly sending commands to thedatabase for commit() or rollback() method calls?

Default Value false

Since Version 3.1.7

• useLocalTransactionState

Should the driver use the in-transaction state provided by the MySQL protocol to determine if a commit()or rollback() should actually be sent to the database?

Default Value false

Since Version 5.1.7

• prepStmtCacheSize

If prepared statement caching is enabled, how many prepared statements should be cached?

Default Value 25


• prepStmtCacheSqlLimit

If prepared statement caching is enabled, what's the largest SQL the driver will cache the parsing for?

Default Value 256


• parseInfoCacheFactory

Name of a class implementing com.mysql.jdbc.CacheAdapterFactory, which will be used to createcaches for the parsed representation of client-side prepared statements.

Default Value com.mysql.jdbc.PerConnectionLRUFactory

Since Version 5.1.1

• serverConfigCacheFactory

Name of a class implementing com.mysql.jdbc.CacheAdapterFactory<String, Map<String, String>>,which will be used to create caches for MySQL server configuration values

Default Value com.mysql.jdbc.PerVmServerConfigCacheFactory

Since Version 5.1.1

• alwaysSendSetIsolation

Should the driver always communicate with the database when Connection.setTransactionIsolation()is called? If set to false, the driver will only communicate with the database when the requestedtransaction isolation is different than the whichever is newer, the last value that was set viaConnection.setTransactionIsolation(), or the value that was read from the server when the

30


connection was established. Note that useLocalSessionState=true will force the same behavior asalwaysSendSetIsolation=false, regardless of how alwaysSendSetIsolation is set.

Default Value true

Since Version 3.1.7

• maintainTimeStats

Should the driver maintain various internal timers to enable idle time calculations as well as moreverbose error messages when the connection to the server fails? Setting this property to false removesat least two calls to System.getCurrentTimeMillis() per query.

Default Value true

Since Version 3.1.9

• useCursorFetch

If connected to MySQL > 5.0.2, and setFetchSize() > 0 on a statement, should that statement usecursor-based fetching to retrieve rows?

Default Value false

Since Version 5.0.0

• blobSendChunkSize

Chunk size to use when sending BLOB/CLOBs via ServerPreparedStatements. Note that this valuecannot exceed the value of "maxAllowedPacket" and, if that is the case, then this value will be correctedautomatically.

Default Value 1048576

Since Version 3.1.9

• cacheCallableStmts

Should the driver cache the parsing stage of CallableStatements

Default Value false

Since Version 3.1.2

• cachePrepStmts

Should the driver cache the parsing stage of PreparedStatements of client-side prepared statements, the"check" for suitability of server-side prepared and server-side prepared statements themselves?

Default Value false


• cacheResultSetMetadata

Should the driver cache ResultSetMetaData for Statements and PreparedStatements? (Req. JDK-1.4+,true/false, default 'false')

Default Value false

31


Since Version 3.1.1

• cacheServerConfiguration

Should the driver cache the results of 'SHOW VARIABLES' and 'SHOW COLLATION' on a per-URLbasis?

Default Value false

Since Version 3.1.5

• defaultFetchSize

The driver will call setFetchSize(n) with this value on all newly-created Statements

Default Value 0

Since Version 3.1.9

• dontCheckOnDuplicateKeyUpdateInSQL

Stops checking if every INSERT statement contains the "ON DUPLICATE KEY UPDATE" clause. Asa side effect, obtaining the statement's generated keys information will return a list where normally itwouldn't. Also be aware that, in this case, the list of generated keys returned may not be accurate. Theeffect of this property is canceled if set simultaneously with 'rewriteBatchedStatements=true'.

Default Value false


• dontTrackOpenResources

The JDBC specification requires the driver to automatically track and close resources, howeverif your application doesn't do a good job of explicitly calling close() on statements or result sets,this can cause memory leakage. Setting this property to true relaxes this constraint, and canbe more memory efficient for some applications. Also the automatic closing of the Statementand current ResultSet in Statement.closeOnCompletion() and Statement.getMoreResults([Statement.CLOSE_CURRENT_RESULT | Statement.CLOSE_ALL_RESULTS]), respectively, ceasesto happen. This property automatically sets holdResultsOpenOverStatementClose=true.

Default Value false

Since Version 3.1.7

• dynamicCalendars

Should the driver retrieve the default calendar when required, or cache it per connection/session?

Default Value false

Since Version 3.1.5

• elideSetAutoCommits

If using MySQL-4.1 or newer, should the driver only issue 'set autocommit=n' queries when the server'sstate doesn't match the requested state by Connection.setAutoCommit(boolean)?

Default Value false

32


Since Version 3.1.3

• enableEscapeProcessing

Sets the default escape processing behavior for Statement objects. The methodStatement.setEscapeProcessing() can be used to specify the escape processing behavior for anindividual Statement object. Default escape processing behavior in prepared statements must be definedwith the property 'processEscapeCodesForPrepStmts'.

Default Value true


• enableQueryTimeouts

When enabled, query timeouts set via Statement.setQueryTimeout() use a shared java.util.Timerinstance for scheduling. Even if the timeout doesn't expire before the query is processed, there willbe memory used by the TimerTask for the given timeout which won't be reclaimed until the time thetimeout would have expired if it hadn't been cancelled by the driver. High-load environments might wantto consider disabling this functionality.

Default Value true

Since Version 5.0.6

• holdResultsOpenOverStatementClose

Should the driver close result sets on Statement.close() as required by the JDBC specification?

Default Value false

Since Version 3.1.7

• largeRowSizeThreshold

What size result set row should the JDBC driver consider "large", and thus use a more memory-efficientway of representing the row internally?

Default Value 2048

Since Version 5.1.1

• loadBalanceStrategy

If using a load-balanced connection to connect to SQL nodes in a MySQL Cluster/NDB configuration(by using the URL prefix "jdbc:mysql:loadbalance://"), which load balancing algorithm should the driveruse: (1) "random" - the driver will pick a random host for each request. This tends to work better thanround-robin, as the randomness will somewhat account for spreading loads where requests vary inresponse time, while round-robin can sometimes lead to overloaded nodes if there are variations inresponse times across the workload. (2) "bestResponseTime" - the driver will route the request to thehost that had the best response time for the previous transaction. (3) "serverAffinity" - the driver initiallyattempts to enforce server affinity while still respecting and benefiting from the fault tolerance aspectsof the load-balancing implementation. The server affinity ordered list is provided using the property'serverAffinityOrder'. If none of the servers listed in the affinity list is responsive, the driver then refers tothe "random" strategy to proceed with choosing the next server.

Default Value random

33


Since Version 5.0.6

• locatorFetchBufferSize

If 'emulateLocators' is configured to 'true', what size buffer should be used when fetching BLOB data forgetBinaryInputStream?

Default Value 1048576

Since Version 3.2.1

• readOnlyPropagatesToServer

Should the driver issue appropriate statements to implicitly set the transaction access mode on serverside when Connection.setReadOnly() is called? Setting this property to 'true' enables InnoDB read-only potential optimizations but also requires an extra roundtrip to set the right transaction state. Even ifthis property is set to 'false', the driver will do its best effort to prevent the execution of database-state-changing queries. Requires minimum of MySQL 5.6.

Default Value true


• rewriteBatchedStatements

Should the driver use multiqueries (irregardless of the setting of "allowMultiQueries") as well as rewritingof prepared statements for INSERT into multi-value inserts when executeBatch() is called? Noticethat this has the potential for SQL injection if using plain java.sql.Statements and your code doesn'tsanitize input correctly. Notice that for prepared statements, if you don't specify stream lengths whenusing PreparedStatement.set*Stream(), the driver won't be able to determine the optimum numberof parameters per batch and you might receive an error from the driver that the resultant packetis too large. Statement.getGeneratedKeys() for these rewritten statements only works when theentire batch includes INSERT statements. Please be aware using rewriteBatchedStatements=truewith INSERT .. ON DUPLICATE KEY UPDATE that for rewritten statement server returns only onevalue as sum of all affected (or found) rows in batch and it isn't possible to map it correctly to initialstatements; in this case driver returns 0 as a result of each batch statement if total count was 0, and theStatement.SUCCESS_NO_INFO as a result of each batch statement if total count was > 0.

Default Value false


• serverAffinityOrder

A comma-separated list containing the host/port pairs that are to be used in load-balancing"serverAffinity" strategy. Only the subset of the hosts enumerated in the main hosts section in this URLwill be used and they must be identical in case and type, i.e., can't use an IP address in one place andthe corresponding host name in the other.


34

Debugging/Profiling

• useDirectRowUnpack

Use newer result set row unpacking code that skips a copy from network buffers to a MySQL packetinstance and instead reads directly into the result set row data buffers.

Default Value true

Since Version 5.1.1

• useDynamicCharsetInfo

Should the driver use a per-connection cache of character set information queried from the server whennecessary, or use a built-in static mapping that is more efficient, but isn't aware of custom character setsor character sets implemented after the release of the JDBC driver?

Default Value true

Since Version 5.0.6

• useFastDateParsing

Use internal String->Date/Time/Timestamp conversion routines to avoid excessive objectcreation? This is part of the legacy date-time code, thus the property has an effect only when"useLegacyDatetimeCode=true."

Default Value true

Since Version 5.0.5

• useFastIntParsing

Use internal String->Integer conversion routines to avoid excessive object creation?

Default Value true

Since Version 3.1.4

• useJvmCharsetConverters

Always use the character encoding routines built into the JVM, rather than using lookup tables for single-byte character sets?

Default Value false

Since Version 5.0.1

• useReadAheadInput

Use newer, optimized non-blocking, buffered input stream when reading from the server?

Default Value true

Since Version 3.1.5

5.3.6 Debugging/Profiling

• logger

35

Debugging/Profiling

The name of a class that implements "com.mysql.jdbc.log.Log" that will be used to log messages to.(default is "com.mysql.jdbc.log.StandardLogger", which logs to STDERR)

Default Value com.mysql.jdbc.log.StandardLogger

Since Version 3.1.1

• gatherPerfMetrics

Should the driver gather performance metrics, and report them via the configured logger every'reportMetricsIntervalMillis' milliseconds?

Default Value false

Since Version 3.1.2

• profileSQL

Trace queries and their execution/fetch times to the configured 'profilerEventHandler'

Default Value false

Since Version 3.1.0

• profileSql

Deprecated, use 'profileSQL' instead. Trace queries and their execution/fetch times on STDERR (true/false) defaults to 'false'


• reportMetricsIntervalMillis

If 'gatherPerfMetrics' is enabled, how often should they be logged (in ms)?

Default Value 30000

Since Version 3.1.2

• maxQuerySizeToLog

Controls the maximum length of the part of a query that will get logged when profiling or tracing

Default Value 2048

Since Version 3.1.3

• packetDebugBufferSize

The maximum number of packets to retain when 'enablePacketDebug' is true

Default Value 20

Since Version 3.1.3

• slowQueryThresholdMillis

If 'logSlowQueries' is enabled, how long should a query take (in ms) before it is logged as slow?

36

Debugging/Profiling

Default Value 2000

Since Version 3.1.2

• slowQueryThresholdNanos

If 'logSlowQueries' is enabled, 'useNanosForElapsedTime' is set to true, and this property is set to a non-zero value, the driver will use this threshold (in nanosecond units) to determine if a query was slow.

Default Value 0

Since Version 5.0.7

• useUsageAdvisor

Should the driver issue 'usage' warnings advising proper and efficient usage of JDBC and MySQLConnector/J to the 'profilerEventHandler'?

Default Value false

Since Version 3.1.1

• autoGenerateTestcaseScript

Should the driver dump the SQL it is executing, including server-side prepared statements to STDERR?

Default Value false

Since Version 3.1.9

• autoSlowLog

Instead of using slowQueryThreshold* to determine if a query is slow enough to be logged, maintainstatistics that allow the driver to determine queries that are outside the 99th percentile?

Default Value true

Since Version 5.1.4

• clientInfoProvider

The name of a class that implements the com.mysql.jdbc.JDBC4ClientInfoProvider interface in order tosupport JDBC-4.0's Connection.get/setClientInfo() methods

Default Value com.mysql.jdbc.JDBC4CommentClientInfoProvider

Since Version 5.1.0

• dumpMetadataOnColumnNotFound

Should the driver dump the field-level metadata of a result set into the exception message whenResultSet.findColumn() fails?

Default Value false

Since Version 3.1.13 37

Debugging/Profiling

• dumpQueriesOnException

Should the driver dump the contents of the query sent to the server in the message for SQLExceptions?

Default Value false

Since Version 3.1.3

• enablePacketDebug

When enabled, a ring-buffer of 'packetDebugBufferSize' packets will be kept, and dumped whenexceptions are thrown in key areas in the driver's code

Default Value false

Since Version 3.1.3

• explainSlowQueries

If 'logSlowQueries' is enabled, should the driver automatically issue an 'EXPLAIN' on the server andsend the results to the configured logger at a WARN level?

Default Value false

Since Version 3.1.2

• includeInnodbStatusInDeadlockExceptions

Include the output of "SHOW ENGINE INNODB STATUS" in exception messages when deadlockexceptions are detected?

Default Value false

Since Version 5.0.7

• includeThreadDumpInDeadlockExceptions

Include a current Java thread dump in exception messages when deadlock exceptions are detected?

Default Value false


• includeThreadNamesAsStatementComment

Include the name of the current thread as a comment visible in "SHOW PROCESSLIST", or in Innodbdeadlock dumps, useful in correlation with "includeInnodbStatusInDeadlockExceptions=true" and"includeThreadDumpInDeadlockExceptions=true".

Default Value false


• logSlowQueries

Should queries that take longer than 'slowQueryThresholdMillis' or detected by the 'autoSlowLog'monitoring be reported to the registered 'profilerEventHandler'?

Default Value false

38

Miscellaneous

Since Version 3.1.2

• logXaCommands

Should the driver log XA commands sent by MysqlXaConnection to the server, at the DEBUG level oflogging?

Default Value false

Since Version 5.0.5

• profilerEventHandler

Name of a class that implements the interface com.mysql.jdbc.profiler.ProfilerEventHandler that will beused to handle profiling/tracing events.

Default Value com.mysql.jdbc.profiler.LoggingProfilerEventHandler

Since Version 5.1.6

• resultSetSizeThreshold

If 'useUsageAdvisor' is true, how many rows should a result set contain before the driver warns that it issuspiciously large?

Default Value 100

Since Version 5.0.5

• traceProtocol

Should the network protocol be logged at the TRACE level?

Default Value false

Since Version 3.1.2

• useNanosForElapsedTime

For profiling/debugging functionality that measures elapsed time, should the driver try to usenanoseconds resolution if available (JDK >= 1.5)?

Default Value false

Since Version 5.0.7

5.3.7 Miscellaneous

• useUnicode

Should the driver use Unicode character encodings when handling strings? Should only be used whenthe driver can't determine the character set mapping, or you are trying to 'force' the driver to use acharacter set that MySQL either doesn't natively support (such as UTF-8), true/false, defaults to 'true'

Default Value true

Since Version 1.1g

• characterEncoding

39

Miscellaneous

If 'useUnicode' is set to true, what character encoding should the driver use when dealing with strings?(defaults is to 'autodetect')

Since Version 1.1g

• characterSetResults

Character set to tell the server to return results as.


• connectionAttributes

A comma-delimited list of user-defined key:value pairs (in addition to standard MySQL-defined key:value pairs) to be passed to MySQL Server for display as connection attributesin the PERFORMANCE_SCHEMA.SESSION_CONNECT_ATTRS table. Example usage:connectionAttributes=key1:value1,key2:value2 This functionality is available for use with MySQL Serverversion 5.6 or later only. Earlier versions of MySQL Server do not support connection attributes, causingthis configuration option to be ignored. Setting connectionAttributes=none will cause connection attributeprocessing to be bypassed, for situations where Connection creation/initialization speed is critical.


• connectionCollation

If set, tells the server to use this collation in SET NAMES charset COLLATE connectionCollation. Alsooverrides the characterEncoding with those corresponding to character set of this collation.


• useBlobToStoreUTF8OutsideBMP

Tells the driver to treat [MEDIUM/LONG]BLOB columns as [LONG]VARCHAR columns holding textencoded in UTF-8 that has characters outside the BMP (4-byte encodings), which MySQL server can'thandle natively.

Default Value false

Since Version 5.1.3

• utf8OutsideBmpExcludedColumnNamePattern

When "useBlobToStoreUTF8OutsideBMP" is set to "true", column names matchingthe given regex will still be treated as BLOBs unless they match the regex specified for"utf8OutsideBmpIncludedColumnNamePattern". The regex must follow the patterns used for thejava.util.regex package.

Since Version 5.1.3

• utf8OutsideBmpIncludedColumnNamePattern

Used to specify exclusion rules to "utf8OutsideBmpExcludedColumnNamePattern". The regex mustfollow the patterns used for the java.util.regex package.

Since Version 5.1.3

40

Miscellaneous

• loadBalanceEnableJMX

Enables JMX-based management of load-balanced connection groups, including live addition/removal ofhosts from load-balancing pool.

Default Value false


• loadBalanceHostRemovalGracePeriod

Sets the grace period to wait for a host being removed from a load-balanced connection, to be releasedwhen it is currently the active host.

Default Value 15000


• sessionVariables

A comma or semicolon separated list of name=value pairs to be sent as SET [SESSION] ... to the serverwhen the driver connects.

Since Version 3.1.8

• useColumnNamesInFindColumn

Prior to JDBC-4.0, the JDBC specification had a bug related to what could be given as a"column name" to ResultSet methods like findColumn(), or getters that took a String property.JDBC-4.0 clarified "column name" to mean the label, as given in an "AS" clause and returned byResultSetMetaData.getColumnLabel(), and if no AS clause, the column name. Setting this property to"true" will give behavior that is congruent to JDBC-3.0 and earlier versions of the JDBC specification, butwhich because of the specification bug could give unexpected results. This property is preferred over"useOldAliasMetadataBehavior" unless you need the specific behavior that it provides with respect toResultSetMetadata.

Default Value false

Since Version 5.1.7

• allowNanAndInf

Should the driver allow NaN or +/- INF values in PreparedStatement.setDouble()?

Default Value false

Since Version 3.1.5

• autoClosePStmtStreams

Should the driver automatically call .close() on streams/readers passed as arguments via set*()methods?

Default Value false


• autoDeserialize

41

Miscellaneous

Should the driver automatically detect and de-serialize objects stored in BLOB fields?

Default Value false

Since Version 3.1.5

• blobsAreStrings

Should the driver always treat BLOBs as Strings - specifically to work around dubious metadata returnedby the server for GROUP BY clauses?

Default Value false

Since Version 5.0.8

• cacheDefaultTimezone

Caches client's default time zone. This results in better performance when dealing with time zoneconversions in Date and Time data types, however it won't be aware of time zone changes if theyhappen at runtime.

Default Value true


• capitalizeTypeNames

Capitalize type names in DatabaseMetaData? (usually only useful when using WebObjects, true/false,defaults to 'false')

Default Value true

Since Version 2.0.7

• clobCharacterEncoding

The character encoding to use for sending and retrieving TEXT, MEDIUMTEXT and LONGTEXT valuesinstead of the configured connection characterEncoding

Since Version 5.0.0

• clobberStreamingResults

This will cause a 'streaming' ResultSet to be automatically closed, and any outstanding data stillstreaming from the server to be discarded if another query is executed before all the data has been readfrom the server.

Default Value false

Since Version 3.0.9

• compensateOnDuplicateKeyUpdateCounts

Should the driver compensate for the update counts of "ON DUPLICATE KEY" INSERT statements (2 =1, 0 = 1) when using prepared statements?

Default Value false

42

Miscellaneous

Since Version 5.1.7

• continueBatchOnError

Should the driver continue processing batch commands if one statement fails. The JDBC spec allowseither way (defaults to 'true').

Default Value true

Since Version 3.0.3

• createDatabaseIfNotExist

Creates the database given in the URL if it doesn't yet exist. Assumes the configured user haspermissions to create databases.

Default Value false

Since Version 3.1.9

• detectCustomCollations

Should the driver detect custom charsets/collations installed on server (true/false, defaults to 'false').If this option set to 'true' driver gets actual charsets/collations from server each time connectionestablishes. This could slow down connection initialization significantly.

Default Value false


• emptyStringsConvertToZero

Should the driver allow conversions from empty string fields to numeric values of '0'?

Default Value true

Since Version 3.1.8

• emulateLocators

Should the driver emulate java.sql.Blobs with locators? With this feature enabled, the driver will delayloading the actual Blob data until the one of the retrieval methods (getInputStream(), getBytes(), and soforth) on the blob data stream has been accessed. For this to work, you must use a column alias with thevalue of the column to the actual name of the Blob. The feature also has the following restrictions: TheSELECT that created the result set must reference only one table, the table must have a primary key;the SELECT must alias the original blob column name, specified as a string, to an alternate name; theSELECT must cover all columns that make up the primary key.

Default Value false

Since Version 3.1.0

• emulateUnsupportedPstmts

Should the driver detect prepared statements that are not supported by the server, and replace themwith client-side emulated versions?

Default Value true

43

Miscellaneous

Since Version 3.1.7

• exceptionInterceptors

Comma-delimited list of classes that implement com.mysql.jdbc.ExceptionInterceptor. These classes willbe instantiated one per Connection instance, and all SQLExceptions thrown by the driver will be allowedto be intercepted by these interceptors, in a chained fashion, with the first class listed as the head of thechain.

Since Version 5.1.8

• functionsNeverReturnBlobs

Should the driver always treat data from functions returning BLOBs as Strings - specifically to workaround dubious metadata returned by the server for GROUP BY clauses?

Default Value false

Since Version 5.0.8

• generateSimpleParameterMetadata

Should the driver generate simplified parameter metadata for PreparedStatements when no metadatais available either because the server couldn't support preparing the statement, or server-side preparedstatements are disabled?

Default Value false

Since Version 5.0.5

• getProceduresReturnsFunctions

Pre-JDBC4 DatabaseMetaData API has only the getProcedures() and getProcedureColumns() methods,so they return metadata info for both stored procedures and functions. JDBC4 was extended withthe getFunctions() and getFunctionColumns() methods and the expected behaviours of previousmethods are not well defined. For JDBC4 and higher, default 'true' value of the option means that callsof DatabaseMetaData.getProcedures() and DatabaseMetaData.getProcedureColumns() return metadatafor both procedures and functions as before, keeping backward compatibility. Setting this property to'false' decouples Connector/J from its pre-JDBC4 behaviours for DatabaseMetaData.getProcedures()and DatabaseMetaData.getProcedureColumns(), forcing them to return metadata for procedures only.

Default Value true


• ignoreNonTxTables

Ignore non-transactional table warning for rollback? (defaults to 'false').

Default Value false

Since Version 3.0.9

• jdbcCompliantTruncation

Should the driver throw java.sql.DataTruncation exceptions when data is truncated as is required by theJDBC specification when connected to a server that supports warnings (MySQL 4.1.0 and newer)? Thisproperty has no effect if the server sql-mode includes STRICT_TRANS_TABLES.

44

Miscellaneous

Default Value true

Since Version 3.1.2

• loadBalanceAutoCommitStatementRegex

When load-balancing is enabled for auto-commit statements (vialoadBalanceAutoCommitStatementThreshold), the statement counter will only increment when the SQLmatches the regular expression. By default, every statement issued matches.


• loadBalanceAutoCommitStatementThreshold

When auto-commit is enabled, the number of statements which should be executed before triggeringload-balancing to rebalance. Default value of 0 causes load-balanced connections to only rebalancewhen exceptions are encountered, or auto-commit is disabled and transactions are explicitly committedor rolled back.

Default Value 0


• loadBalanceBlacklistTimeout

Time in milliseconds between checks of servers which are unavailable, by controlling how long a serverlives in the global blocklist.

Default Value 0

Since Version 5.1.0

• loadBalanceConnectionGroup

Logical group of load-balanced connections within a classloader, used to manage different groupsindependently. If not specified, live management of load-balanced connections is disabled.


• loadBalanceExceptionChecker

Fully-qualified class name of custom exception checker. The class must implementcom.mysql.jdbc.LoadBalanceExceptionChecker interface, and is used to inspect SQLExceptions anddetermine whether they should trigger fail-over to another host in a load-balanced deployment.

Default Value com.mysql.jdbc.StandardLoadBalanceExceptionChecker


• loadBalancePingTimeout

Time in milliseconds to wait for ping response from each of load-balanced physical connections whenusing load-balanced Connection.

Default Value 0


45

Miscellaneous

• loadBalanceSQLExceptionSubclassFailover

Comma-delimited list of classes/interfaces used by default load-balanced exception checker todetermine whether a given SQLException should trigger failover. The comparison is done usingClass.isInstance(SQLException) using the thrown SQLException.


• loadBalanceSQLStateFailover

Comma-delimited list of SQLState codes used by default load-balanced exception checker to determinewhether a given SQLException should trigger failover. The SQLState of a given SQLException isevaluated to determine whether it begins with any value in the comma-delimited list.


• loadBalanceValidateConnectionOnSwapServer

Should the load-balanced Connection explicitly check whether the connection is live when swapping to anew physical connection at commit/rollback?

Default Value false


• maxRows

The maximum number of rows to return (0, the default means return all rows).

Default Value -1


• netTimeoutForStreamingResults

What value should the driver automatically set the server setting 'net_write_timeout' to when thestreaming result sets feature is in use? (value has unit of seconds, the value '0' means the driver will nottry and adjust this value)

Default Value 600

Since Version 5.1.0

• noAccessToProcedureBodies

When determining procedure parameter types for CallableStatements, and the connected user can'taccess procedure bodies through "SHOW CREATE PROCEDURE" or select on mysql.proc shouldthe driver instead create basic metadata (all parameters reported as IN VARCHARs, but allowingregisterOutParameter() to be called on them anyway) instead of throwing an exception?

Default Value false

Since Version 5.0.3

46

Miscellaneous

• noDatetimeStringSync

Don't ensure that ResultSet.getDatetimeType().toString().equals(ResultSet.getString())

Default Value false

Since Version 3.1.7

• noTimezoneConversionForDateType

Don't convert DATE values using the server time zone if 'useTimezone'='true' or'useLegacyDatetimeCode'='false'

Default Value true


• noTimezoneConversionForTimeType

Don't convert TIME values using the server time zone if 'useTimezone'='true'

Default Value false

Since Version 5.0.0

• nullCatalogMeansCurrent

When DatabaseMetadataMethods ask for a 'catalog' parameter, does the value null mean use thecurrent catalog? (this is not JDBC-compliant, but follows legacy behavior from earlier versions of thedriver)

Default Value true

Since Version 3.1.8

• nullNamePatternMatchesAll

Should DatabaseMetaData methods that accept *pattern parameters treat null the same as '%' (this isnot JDBC-compliant, however older versions of the driver accepted this departure from the specification)

Default Value true

Since Version 3.1.8

• overrideSupportsIntegrityEnhancementFacility

Should the driver return "true" for DatabaseMetaData.supportsIntegrityEnhancementFacility() even if thedatabase doesn't support it to workaround applications that require this method to return "true" to signalsupport of foreign keys, even though the SQL specification states that this facility contains much morethan just foreign key support (one such application being OpenOffice)?

Default Value false


47

Miscellaneous

• padCharsWithSpace

If a result set column has the CHAR type and the value does not fill the amount of characters specifiedin the DDL for the column, should the driver pad the remaining characters with space (for ANSIcompliance)?

Default Value false

Since Version 5.0.6

• pedantic

Follow the JDBC spec to the letter.

Default Value false

Since Version 3.0.0

• pinGlobalTxToPhysicalConnection

When using XAConnections, should the driver ensure that operations on a given XID are always routedto the same physical connection? This allows the XAConnection to support "XA START ... JOIN" after"XA END" has been called

Default Value false

Since Version 5.0.1

• populateInsertRowWithDefaultValues

When using ResultSets that are CONCUR_UPDATABLE, should the driver pre-populate the "insert"row with default values from the DDL for the table used in the query so those values are immediatelyavailable for ResultSet accessors? This functionality requires a call to the database for metadata eachtime a result set of this type is created. If disabled (the default), the default values will be populated bythe an internal call to refreshRow() which pulls back default values and/or values changed by triggers.

Default Value false

Since Version 5.0.5

• processEscapeCodesForPrepStmts

Should the driver process escape codes in queries that are prepared? Default escape processingbehavior in non-prepared statements must be defined with the property 'enableEscapeProcessing'.

Default Value true


• queryTimeoutKillsConnection

If the timeout given in Statement.setQueryTimeout() expires, should the driver forcibly abort theConnection instead of attempting to abort the query?

Default Value false

Since Version 5.1.9

• relaxAutoCommit

48

Miscellaneous

If the version of MySQL the driver connects to does not support transactions, still allow calls to commit(),rollback() and setAutoCommit() (true/false, defaults to 'false')?

Default Value false


• retainStatementAfterResultSetClose

Should the driver retain the Statement reference in a ResultSet after ResultSet.close() has been called.This is not JDBC-compliant after JDBC-4.0.

Default Value false


• rollbackOnPooledClose

Should the driver issue a rollback() when the logical connection in a pool is closed?

Default Value true


• runningCTS13

Enables workarounds for bugs in Sun's JDBC compliance testsuite version 1.3

Default Value false

Since Version 3.1.7

• sendFractionalSeconds

Send fractional part from TIMESTAMP seconds. If set to false, the nanoseconds value of TIMESTAMPvalues will be truncated before sending any data to the server. This option applies only to preparedstatements, callable statements or updatable result sets.

Default Value true


• serverTimezone

Override detection/mapping of time zone. Used when time zone from server doesn't map to Java timezone

Since Version 3.0.2

• statementInterceptors

A comma-delimited list of classes that implement "com.mysql.jdbc.StatementInterceptor" that should beplaced "in between" query execution to influence the results. StatementInterceptors are "chainable", theresults returned by the "current" interceptor will be passed on to the next in in the chain, from left-to-rightorder, as specified in this property.

Since Version 5.1.1

49

Miscellaneous

• strictFloatingPoint

Used only in older versions of compliance test

Default Value false

Since Version 3.0.0

• strictUpdates

Should the driver perform strict checking (all primary keys selected) of updatable result sets (true, false,defaults to 'true')?

Default Value true

Since Version 3.0.4

• tinyInt1isBit

Should the driver treat the datatype TINYINT(1) as the BIT type (because the server silently converts BIT-> TINYINT(1) when creating tables)?

Default Value true


• transformedBitIsBoolean

If the driver converts TINYINT(1) to a different type, should it use BOOLEAN instead of BIT for futurecompatibility with MySQL-5.0, as MySQL-5.0 has a BIT type?

Default Value false

Since Version 3.1.9

• treatUtilDateAsTimestamp

Should the driver treat java.util.Date as a TIMESTAMP for the purposes ofPreparedStatement.setObject()?

Default Value true

Since Version 5.0.5

• ultraDevHack

Create PreparedStatements for prepareCall() when required, because UltraDev is broken and issues aprepareCall() for _all_ statements? (true/false, defaults to 'false')

Default Value false

Since Version 2.0.3

• useAffectedRows

Don't set the CLIENT_FOUND_ROWS flag when connecting to the server (not JDBC-compliant, willbreak most applications that rely on "found" rows vs. "affected rows" for DML statements), but doescause "correct" update counts from "INSERT ... ON DUPLICATE KEY UPDATE" statements to bereturned by the server.

50

Miscellaneous

Default Value false

Since Version 5.1.7

• useGmtMillisForDatetimes

Convert between session time zone and GMT before creating Date and Timestamp instances (value of'false' leads to legacy behavior, 'true' leads to more JDBC-compliant behavior)? This is part of the legacydate-time code, thus the property has an effect only when "useLegacyDatetimeCode=true."

Default Value false


• useHostsInPrivileges

Add '@hostname' to users in DatabaseMetaData.getColumn/TablePrivileges() (true/false), defaults to'true'.

Default Value true

Since Version 3.0.2

• useInformationSchema

When connected to MySQL-5.0.7 or newer, should the driver use the INFORMATION_SCHEMA toderive information used by DatabaseMetaData?

Default Value false

Since Version 5.0.0

• useJDBCCompliantTimezoneShift

Should the driver use JDBC-compliant rules when converting TIME/TIMESTAMP/DATETIME values'time zone information for those JDBC arguments which take a java.util.Calendar argument? This is partof the legacy date-time code, thus the property has an effect only when "useLegacyDatetimeCode=true."

Default Value false

Since Version 5.0.0

• useLegacyDatetimeCode

Use code for DATE/TIME/DATETIME/TIMESTAMP handling in result sets and statements thatconsistently handles time zone conversions from client to server and back again, or use the legacy codefor these datatypes that has been in the driver for backwards-compatibility? Setting this property to 'false'voids the effects of "useTimezone," "useJDBCCompliantTimezoneShift," "useGmtMillisForDatetimes,"and "useFastDateParsing."

Default Value true

Since Version 5.1.6

51

Miscellaneous

• useOldAliasMetadataBehavior

Should the driver use the legacy behavior for "AS" clauses on columns and tables, and only returnaliases (if any) for ResultSetMetaData.getColumnName() or ResultSetMetaData.getTableName() ratherthan the original column/table name? In 5.0.x, the default value was true.

Default Value false

Since Version 5.0.4

• useOldUTF8Behavior

Use the UTF-8 behavior the driver did when communicating with 4.0 and older servers

Default Value false

Since Version 3.1.6

• useOnlyServerErrorMessages

Don't prepend 'standard' SQLState error messages to error messages returned by the server.

Default Value true


• useSSPSCompatibleTimezoneShift

If migrating from an environment that was using server-side prepared statements, and the configurationproperty "useJDBCCompliantTimeZoneShift" set to "true", use compatible behavior when not usingserver-side prepared statements when sending TIMESTAMP values to the MySQL server.

Default Value false

Since Version 5.0.5

• useServerPrepStmts

Use server-side prepared statements if the server supports them?

Default Value false

Since Version 3.1.0

• useSqlStateCodes

Use SQL Standard state codes instead of 'legacy' X/Open/SQL state codes (true/false), default is 'true'

Default Value true

Since Version 3.1.3

• useStreamLengthsInPrepStmts

Honor stream length parameter in PreparedStatement/ResultSet.setXXXStream() method calls (true/false, defaults to 'true')?

Default Value true

Since Version 3.0.2

52

The useConfigs Option and the Configuration Property Files

• useTimezone

Convert time/date types between client and server time zones (true/false, defaults to 'false')? This is partof the legacy date-time code, thus the property has an effect only when "useLegacyDatetimeCode=true."

Default Value false

Since Version 3.0.2

• useUnbufferedInput

Don't use BufferedInputStream for reading data from the server

Default Value true


• yearIsDateType

Should the JDBC driver treat the MySQL type "YEAR" as a java.sql.Date, or as a SHORT?

Default Value true

Since Version 3.1.9

• zeroDateTimeBehavior

What should happen when the driver encounters DATETIME values that are composed entirely of zeros(used by MySQL to represent invalid dates)? Valid values are "exception", "round" and "convertToNull".

Default Value exception

Since Version 3.1.4

5.3.8 The useConfigs Option and the Configuration Property Files

The useConfigs connection option is convenient shorthand for specifying combinations of optionsfor particular scenarios. The argument values you can use with this option correspond to the names of.properties files within the Connector/J mysql-connector-java-version-bin.jar JAR file. Forexample, the Connector/J 5.1.9 driver includes the following configuration properties files:

$ unzip mysql-connector-java-5.1.19-bin.jar '*/configs/*'Archive: mysql-connector-java-5.1.19-bin.jar creating: com/mysql/jdbc/configs/ inflating: com/mysql/jdbc/configs/3-0-Compat.properties inflating: com/mysql/jdbc/configs/5-0-Compat.properties inflating: com/mysql/jdbc/configs/clusterBase.properties inflating: com/mysql/jdbc/configs/coldFusion.properties inflating: com/mysql/jdbc/configs/fullDebug.properties inflating: com/mysql/jdbc/configs/maxPerformance.properties inflating: com/mysql/jdbc/configs/solarisMaxPerformance.properties

To specify one of these combinations of options, specify useConfigs=3-0-Compat,useConfigs=maxPerformance, and so on. The following sections show the options that are part of eachuseConfigs setting. For the details of why each one is included, see the comments in the .propertiesfiles.

3-0-Compat

emptyStringsConvertToZero=true

53

JDBC API Implementation Notes

jdbcCompliantTruncation=falsenoDatetimeStringSync=truenullCatalogMeansCurrent=truenullNamePatternMatchesAll=truetransformedBitIsBoolean=falsedontTrackOpenResources=truezeroDateTimeBehavior=convertToNulluseServerPrepStmts=falseautoClosePStmtStreams=trueprocessEscapeCodesForPrepStmts=falseuseFastDateParsing=falsepopulateInsertRowWithDefaultValues=falseuseDirectRowUnpack=false

5-0-Compat

useDirectRowUnpack=false

clusterBase

autoReconnect=truefailOverReadOnly=falseroundRobinLoadBalance=true

coldFusion

useDynamicCharsetInfo=falsealwaysSendSetIsolation=falseuseLocalSessionState=trueautoReconnect=true

fullDebug

profileSQL=truegatherPerfMetrics=trueuseUsageAdvisor=truelogSlowQueries=trueexplainSlowQueries=true

maxPerformance

cachePrepStmts=truecacheCallableStmts=truecacheServerConfiguration=trueuseLocalSessionState=trueelideSetAutoCommits=truealwaysSendSetIsolation=falseenableQueryTimeouts=false

solarisMaxPerformance

useUnbufferedInput=falseuseReadAheadInput=falsemaintainTimeStats=false

5.4 JDBC API Implementation NotesMySQL Connector/J, as a rigorous implementation of the JDBC API, passes all of the tests in the publiclyavailable version of Oracle's JDBC compliance test suite. The JDBC specification is flexible on how certainfunctionality should be implemented. This section gives details on an interface-by-interface level aboutimplementation decisions that might affect how you code applications with MySQL Connector/J.

• BLOB

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http://www.oracle.com/technetwork/java/javase/jdbc/index.html


Starting with Connector/J version 3.1.0, you can emulate BLOBs with locators by adding the propertyemulateLocators=true to your JDBC URL. Using this method, the driver will delay loading the actualBLOB data until you retrieve the other data and then use retrieval methods (getInputStream(),getBytes(), and so forth) on the BLOB data stream.

You must use a column alias with the value of the column to the actual name of the BLOB, for example:

SELECT id, 'data' as blob_data from blobtable

You must also follow these rules:

• The SELECT must reference only one table. The table must have a primary key.

• The SELECT must alias the original BLOB column name, specified as a string, to an alternate name.

• The SELECT must cover all columns that make up the primary key.

The BLOB implementation does not allow in-place modification (they are copies, as reported by theDatabaseMetaData.locatorsUpdateCopies() method). Because of this, use the correspondingPreparedStatement.setBlob() or ResultSet.updateBlob() (in the case of updatable resultsets) methods to save changes back to the database.

• CallableStatement

Starting with Connector/J 3.1.1, stored procedures are supported when connecting to MySQL version5.0 or newer using the CallableStatement interface. Currently, the getParameterMetaData()method of CallableStatement is not supported.

• Connection

Unlike the pre-Connector/J JDBC driver (MM.MySQL), the isClosed() method does not ping the serverto determine if it is available. In accordance with the JDBC specification, it only returns true if closed()has been called on the connection. If you need to determine if the connection is still valid, issue a simplequery, such as SELECT 1. The driver will throw an exception if the connection is no longer valid.

• DatabaseMetaData

Foreign key information (getImportedKeys()/getExportedKeys() and getCrossReference())is only available from InnoDB tables. The driver uses SHOW CREATE TABLE to retrieve this information,so if any other storage engines add support for foreign keys, the driver would transparently support themas well.

• PreparedStatement

Two variants of prepared statements are implemented by Connector/J, the client-side and the server-side prepared statements. Client-side prepared statements are used by default because early MySQLversions did not support the prepared statement feature or had problems with its implementation. Server-side prepared statements and binary-encoded result sets are used when the server supports them. Toenable usage of server-side prepared statements, set useServerPrepStmts=true.

Be careful when using a server-side prepared statement with large parameters that are set usingsetBinaryStream(), setAsciiStream(), setUnicodeStream(), setCharacterStream(),setNCharacterStream(), setBlob(), setClob(), or setNCLob(). To re-execute the statement

55


https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/glossary.html#glos_primary_key



https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/glossary.html#glos_foreign_key

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/innodb-storage-engine.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/show-create-table.html


with any large parameter changed to a nonlarge parameter, call clearParameters() and set allparameters again. The reason for this is as follows:

• During both server-side prepared statements and client-side emulation, large data is exchanged onlywhen PreparedStatement.execute() is called.

• Once that has been done, the stream used to read the data on the client side is closed (as per theJDBC spec), and cannot be read from again.

• If a parameter changes from large to nonlarge, the driver must reset the server-side state of theprepared statement to allow the parameter that is being changed to take the place of the prior largevalue. This removes all of the large data that has already been sent to the server, thus requiring thedata to be re-sent, using the setBinaryStream(), setAsciiStream(), setUnicodeStream(),setCharacterStream(), setNCharacterStream(), setBlob(), setClob(), or setNCLob()method.

Consequently, to change the type of a parameter to a nonlarge one, you must callclearParameters() and set all parameters of the prepared statement again before it can be re-executed.

• ResultSet

By default, ResultSets are completely retrieved and stored in memory. In most cases this is the mostefficient way to operate and, due to the design of the MySQL network protocol, is easier to implement.If you are working with ResultSets that have a large number of rows or large values and cannot allocateheap space in your JVM for the memory required, you can tell the driver to stream the results back onerow at a time.

To enable this functionality, create a Statement instance in the following manner:

stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY, java.sql.ResultSet.CONCUR_READ_ONLY);stmt.setFetchSize(Integer.MIN_VALUE);

The combination of a forward-only, read-only result set, with a fetch size of Integer.MIN_VALUEserves as a signal to the driver to stream result sets row-by-row. After this, any result sets created withthe statement will be retrieved row-by-row.

There are some caveats with this approach. You must read all of the rows in the result set (or close it)before you can issue any other queries on the connection, or an exception will be thrown.

The earliest the locks these statements hold can be released (whether they be MyISAM table-level locksor row-level locks in some other storage engine such as InnoDB) is when the statement completes.

If the statement is within scope of a transaction, then locks are released when the transaction completes(which implies that the statement needs to complete first). As with most other databases, statementsare not complete until all the results pending on the statement are read or the active result set for thestatement is closed.

Therefore, if using streaming results, process them as quickly as possible if you want to maintainconcurrent access to the tables referenced by the statement producing the result set.

Another alternative is to use cursor-based streaming to retrieve a set number of rows each time.This can be done by setting the connection property useCursorFetch to true, and then callingsetFetchSize(int) with int being the desired number of rows to be fetched each time:

conn = DriverManager.getConnection("jdbc:mysql://localhost/?useCursorFetch=true", "user", "s3cr3t");

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Java, JDBC and MySQL Types

stmt = conn.createStatement();stmt.setFetchSize(100);rs = stmt.executeQuery("SELECT * FROM your_table_here");

• ResultSetMetaData

The isAutoIncrement() method only works when using MySQL servers 4.0 and newer.

• Statement

When using versions of the JDBC driver earlier than 3.2.1, and connected to server versions earlierthan 5.0.3, the setFetchSize() method has no effect, other than to toggle result set streaming asdescribed above.

Connector/J 5.0.0 and later include support for both Statement.cancel() andStatement.setQueryTimeout(). Both require MySQL 5.0.0 or newer server, and require aseparate connection to issue the KILL QUERY statement. In the case of setQueryTimeout(), theimplementation creates an additional thread to handle the timeout functionality.

Note

Failures to cancel the statement for setQueryTimeout() may manifestthemselves as RuntimeException rather than failing silently, as there iscurrently no way to unblock the thread that is executing the query being cancelleddue to timeout expiration and have it throw the exception instead.

Note

The MySQL statement KILL QUERY (which is what the driver uses toimplement Statement.cancel()) is non-deterministic; thus, avoid the useof Statement.cancel() if possible. If no query is in process, the next queryissued will be killed by the server. This race condition is guarded against as ofConnector/J 5.1.18.

MySQL does not support SQL cursors, and the JDBC driver doesn't emulate them, sosetCursorName() has no effect.

Connector/J 5.1.3 and later include two additional methods:

• setLocalInfileInputStream() sets an InputStream instance that will be used to send data tothe MySQL server for a LOAD DATA LOCAL INFILE statement rather than a FileInputStream orURLInputStream that represents the path given as an argument to the statement.

This stream will be read to completion upon execution of a LOAD DATA LOCAL INFILE statement,and will automatically be closed by the driver, so it needs to be reset before each call to execute*()that would cause the MySQL server to request data to fulfill the request for LOAD DATA LOCALINFILE.

If this value is set to NULL, the driver will revert to using a FileInputStream or URLInputStreamas required.

• getLocalInfileInputStream() returns the InputStream instance that will be used to send datain response to a LOAD DATA LOCAL INFILE statement.

This method returns NULL if no such stream has been set using setLocalInfileInputStream().

5.5 Java, JDBC and MySQL Types

57

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/kill.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/kill.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/load-data.html






MySQL Connector/J is flexible in the way it handles conversions between MySQL data types and Javadata types.

In general, any MySQL data type can be converted to a java.lang.String, and any numeric typecan be converted to any of the Java numeric types, although round-off, overflow, or loss of precision mayoccur.

Note

All TEXT types return Types.LONGVARCHAR with different getPrecision()values (65535, 255, 16777215, and 2147483647 respectively) withgetColumnType() returning -1. This behavior is intentional even thoughTINYTEXT does not fall, regarding to its size, within the LONGVARCHARcategory. This is to avoid different handling inside the same base type. AndgetColumnType() returns -1 because the internal server handling is of typeTEXT, which is similar to BLOB.

Also note that getColumnTypeName() will return VARCHAR even thoughgetColumnType() returns Types.LONGVARCHAR, because VARCHAR is thedesignated column database-specific name for this type.

Starting with Connector/J 3.1.0, the JDBC driver issues warnings or throws DataTruncation exceptionsas is required by the JDBC specification unless the connection was configured not to do so by using theproperty jdbcCompliantTruncation and setting it to false.

The conversions that are always guaranteed to work are listed in the following table. The first column listsone or more MySQL data types, and the second column lists one or more Java types to which the MySQLtypes can be converted.

Table 5.1 Possible Conversions Between MySQL and Java Data Types

These MySQL Data Types Can always be converted to these Java types

CHAR, VARCHAR, BLOB, TEXT, ENUM, andSET

java.lang.String, java.io.InputStream,java.io.Reader, java.sql.Blob,java.sql.Clob

FLOAT, REAL, DOUBLE PRECISION,NUMERIC, DECIMAL, TINYINT, SMALLINT,MEDIUMINT, INTEGER, BIGINT

java.lang.String, java.lang.Short,java.lang.Integer, java.lang.Long,java.lang.Double, java.math.BigDecimal

DATE, TIME, DATETIME, TIMESTAMP java.lang.String, java.sql.Date,java.sql.Timestamp

Note

Round-off, overflow or loss of precision may occur if you choose a Java numericdata type that has less precision or capacity than the MySQL data type you areconverting to/from.

The ResultSet.getObject() method uses the type conversions between MySQL andJava types, following the JDBC specification where appropriate. The values returned byResultSetMetaData.GetColumnTypeName()and ResultSetMetaData.GetColumnClassName()are shown in the table below. For more information on the JDBC types, see the reference on thejava.sql.Types class.

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Table 5.2 MySQL Types and Return Values for ResultSetMetaData.GetColumnTypeName()andResultSetMetaData.GetColumnClassName()

MySQL Type Name Return value ofGetColumnTypeName

Return value of GetColumnClassName

BIT(1) (new inMySQL-5.0)

BIT java.lang.Boolean

BIT( > 1) (new inMySQL-5.0)

BIT byte[]

TINYINT TINYINT java.lang.Boolean if the configuration propertytinyInt1isBit is set to true (the default) andthe storage size is 1, or java.lang.Integer ifnot.

BOOL, BOOLEAN TINYINT See TINYINT, above as these are aliases forTINYINT(1), currently.

SMALLINT[(M)][UNSIGNED]

SMALLINT [UNSIGNED] java.lang.Integer (regardless of whether it isUNSIGNED or not)

MEDIUMINT[(M)][UNSIGNED]

MEDIUMINT[UNSIGNED]

java.lang.Integer (regardless of whether it isUNSIGNED or not)

INT,INTEGER[(M)][UNSIGNED]

INTEGER [UNSIGNED] java.lang.Integer, if UNSIGNEDjava.lang.Long

BIGINT[(M)][UNSIGNED]

BIGINT [UNSIGNED] java.lang.Long, if UNSIGNEDjava.math.BigInteger

FLOAT[(M,D)] FLOAT java.lang.Float

DOUBLE[(M,B)] DOUBLE java.lang.Double

DECIMAL[(M[,D])] DECIMAL java.math.BigDecimal

DATE DATE java.sql.Date

DATETIME DATETIME java.sql.Timestamp

TIMESTAMP[(M)] TIMESTAMP java.sql.Timestamp

TIME TIME java.sql.Time

YEAR[(2|4)] YEAR If yearIsDateType configuration property isset to false, then the returned object type isjava.sql.Short. If set to true (the default), thenthe returned object is of type java.sql.Date withthe date set to January 1st, at midnight.

CHAR(M) CHAR java.lang.String (unless the character set forthe column is BINARY, then byte[] is returned.

VARCHAR(M) [BINARY] VARCHAR java.lang.String (unless the character set forthe column is BINARY, then byte[] is returned.

BINARY(M) BINARY byte[]

VARBINARY(M) VARBINARY byte[]

TINYBLOB TINYBLOB byte[]

TINYTEXT VARCHAR java.lang.String

BLOB BLOB byte[]

TEXT VARCHAR java.lang.String

59

Using Character Sets and Unicode

MySQL Type Name Return value ofGetColumnTypeName

Return value of GetColumnClassName

MEDIUMBLOB MEDIUMBLOB byte[]

MEDIUMTEXT VARCHAR java.lang.String

LONGBLOB LONGBLOB byte[]

LONGTEXT VARCHAR java.lang.String

ENUM('value1','value2',...)CHAR java.lang.String

SET('value1','value2',...)CHAR java.lang.String

5.6 Using Character Sets and UnicodeAll strings sent from the JDBC driver to the server are converted automatically from native Java Unicodeform to the client character encoding, including all queries sent using Statement.execute(),Statement.executeUpdate(), Statement.executeQuery() as well as all PreparedStatementand CallableStatement parameters with the exclusion of parameters set using setBytes(),setBinaryStream(), setAsciiStream(), setUnicodeStream(), and setBlob().

Number of Encodings Per Connection

Connector/J supports a single character encoding between client and server, and any number of characterencodings for data returned by the server to the client in ResultSets.

Setting the Character Encoding

The character encoding between client and server is automatically detected upon connection (providedthat the Connector/J connection properties characterEncoding and connectionCollation are notset). You specify the encoding on the server using the system variable character_set_server (formore information, see Server Character Set and Collation). The driver automatically uses the encodingspecified by the server. For example, to use the 4-byte UTF-8 character set with Connector/J, configurethe MySQL server with character_set_server=utf8mb4, and leave characterEncoding andconnectionCollation out of the Connector/J connection string. Connector/J will then autodetect theUTF-8 setting.

To override the automatically detected encoding on the client side, use the characterEncoding propertyin the connection URL to the server. Use Java-style names when specifying character encodings. Thefollowing table lists MySQL character set names and their corresponding Java-style names:

Table 5.3 MySQL to Java Encoding Name Translations

MySQL Character Set Name Java-Style Character Encoding Name

ascii US-ASCII

big5 Big5

gbk GBK

sjis SJIS (or Cp932 or MS932 for MySQLServer < 4.1.11)

cp932 Cp932 or MS932 (MySQL Server > 4.1.11)

gb2312 EUC_CN

ujis EUC_JP

euckr EUC_KR

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/charset-server.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/charset-unicode-utf8mb4.html


Connecting Securely Using SSL

MySQL Character Set Name Java-Style Character Encoding Name

latin1 Cp1252

latin2 ISO8859_2

greek ISO8859_7

hebrew ISO8859_8

cp866 Cp866

tis620 TIS620

cp1250 Cp1250

cp1251 Cp1251

cp1257 Cp1257

macroman MacRoman

macce MacCentralEurope

For 5.1.46 and earlier: utf8

For 5.1.47 and later: utf8mb4

UTF-8

ucs2 UnicodeBig

Notes

For Connector/J 5.1.46 and earlier: In order to use the utf8mb4character set for the connection, the server MUST be configured withcharacter_set_server=utf8mb4; if that is not the case, when UTF-8 isused for characterEncoding in the connection string, it will map to the MySQLcharacter set name utf8, which is an alias for utf8mb3.

For Connector/J 5.1.47 and later:

• When UTF-8 is used for characterEncoding in the connection string, it mapsto the MySQL character set name utf8mb4.

• If the connection option connectionCollation is also set alongsidecharacterEncoding and is incompatible with it, characterEncoding will beoverridden with the encoding corresponding to connectionCollation.

• Because there is no Java-style character set name for utfmb3 that you can usewith the connection option charaterEncoding, the only way to use utf8mb3as your connection character set is to use a utf8mb3 collation (for example,utf8_general_ci) for the connection option connectionCollation, whichforces a utf8mb3 character set to be used, as explained in the last bullet.

Warning

Do not issue the query SET NAMES with Connector/J, as the driver will not detectthat the character set has been changed by the query, and will continue to use thecharacter set configured when the connection was first set up.

5.7 Connecting Securely Using SSL

Connector/J can encrypt all data communicated between the JDBC driver and the server (except for theinitial handshake) using SSL. There is a performance penalty for enabling connection encryption, the

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/set-names.html

Setting up Server Authentication

severity of which depends on multiple factors including (but not limited to) the size of the query, the amountof data returned, the server hardware, the SSL library used, the network bandwidth, and so on.

The system works through two Java keystore files: one file contains the certificate information for theserver (truststore in the examples below), and another contains the keys and certificate for the client(keystore in the examples below). All Java keystore files are protected by the password supplied to thekeytool when you created the files. You need the file names and the associated passwords to create anSSL connection.

For SSL support to work, you must have the following:

• A MySQL server that supports SSL, and compiled and configured to do so. For more information, seeUsing Encrypted Connections and Configuring SSL Library Support.

• A signed client certificate, if using mutual (two-way) authentication.

By default, Connector/J establishes secure connections with the MySQL servers. Note that MySQL servers5.7 and 8.0, when compiled with OpenSSL, can automatically generate missing SSL files at startup andconfigure the SSL connection accordingly.

As long as the server is correctly configured to use SSL, there is no need to configure anything on theConnector/J client to use encrypted connections (the exception is when Connector/J is connecting tovery old server versions like 5.6.25 and earlier or 5.7.5 and earlier, in which case the client must set theconnection property useSSL=true in order to use encrypted connections). The client can demand SSL tobe used by setting the connection property requireSSL=true; the connection then fails if the server isnot configured to use SSL. Without requireSSL=true, the connection just falls back to non-encryptedmode if the server is not configured to use SSL.

For additional security, you can setup the client for a one-way (server or client) or two-way (server andclient) SSL authentication, allowing the client or the server to authenticate each other's identity.

Setting up Server Authentication

Server authentication via server certificate verification is enabled when the Connector/J connectionproperty verifyServerCertificate is true (which is the default setting when useSSL=true).

Note

Standard Java SSL sockets do not support hostname verification, thus Connector/Jdoes not support it. Host authentication is by certificates only.

Certificates signed by a trusted CA. When verifyServerCertificate=true (which is the defaultwhen useSSL is true), if no additional configurations are made regarding server authentication, Javaverifies the server certificate using its default trusted CA certificates, usually from $JAVA_HOME/lib/security/cacerts.

Using self-signed certificates. It is pretty common though for MySQL server certificates to be selfsigned or signed by a self-signed CA certificate; the auto-generated certificates and keys created by theMySQL server are based on the latter—that is, the server generates all required keys and a self-signed CAcertificate that is used to sign a server and a client certificate. The server then configures itself to use theCA certificate and the server certificate. Although the client certificate file is placed in the same directory, itis not used by the server.

To verify the server certificate, Connector/J needs to be able to read the certificate that signed it, thatis, the server certificate that signed itself or the self-signed CA certificate. This can be accomplished byeither importing the certificate (ca.pem or any other certificate) into the Java default truststore (althoughtampering the default truststore is not recommended) or by importing it into a custom Java truststore

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Setting up Client Authentication

file and configuring the Connector/J driver accordingly. Use Java's keytool (typically located in the binsubdirectory of your JDK or JRE installation) to import the server certificates:

$> keytool -importcert -alias MySQLCACert -file ca.pem \ -keystore truststore -storepass mypassword

Supply the proper arguments for the command options. If the truststore file does not already exist, a newone will be created; otherwise the certificate will be added to the existing file. Interaction with keytoollooks like this:

Owner: CN=MySQL_Server_5.7.17_Auto_Generated_CA_CertificateIssuer: CN=MySQL_Server_5.7.17_Auto_Generated_CA_CertificateSerial number: 1Valid from: Thu Feb 16 11:42:43 EST 2017 until: Sun Feb 14 11:42:43 EST 2027Certificate fingerprints: MD5: 18:87:97:37:EA:CB:0B:5A:24:AB:27:76:45:A4:78:C1 SHA1: 2B:0D:D9:69:2C:99:BF:1E:2A:25:4E:8D:2D:38:B8:70:66:47:FA:ED SHA256: C3:29:67:1B:E5:37:06:F7:A9:93:DF:C7:B3:27:5E:09:C7:FD:EE:2D:18:86:F4:9C:40:D8:26:CB:DA:95:A0:24Signature algorithm name: SHA256withRSASubject Public Key Algorithm: 2048-bit RSA keyVersion: 1Trust this certificate? [no]: yesCertificate was added to keystore

The output of the command shows all details about the imported certificate. Make sure you remember thepassword you have supplied. Also, be mindful that the password will have to be written as plain text in yourConnector/J configuration file or application source code.

The next step is to configure Java or Connector/J to read the truststore you just created or modified. Thiscan be done by using one of the following three methods:

• Using the Java command line arguments:

-Djavax.net.ssl.trustStore=path_to_truststore_file -Djavax.net.ssl.trustStorePassword=mypassword

• Setting the system properties directly in the client code:

System.setProperty("javax.net.ssl.trustStore","path_to_truststore_file"); System.setProperty("javax.net.ssl.trustStorePassword","mypassword");

• Setting the Connector/J connection properties:

trustCertificateKeyStoreUrl=file:path_to_truststore_file trustCertificateKeyStorePassword=mypassword

Notice that when used together, the connection properties override the values set by the other twomethods. Also, whatever values set with connection properties are used in that connection only, whilevalues set using the system-wide values are used for all connections (unless overridden by the connectionproperties).

With the above setup and the connection property verifyServerCertificate=true, all connectionsestablished are going to be SSL-encrypted, with the server being authenticated in the SSL handshakeprocess, and the client can now safely trust the server it is connecting to.


The server may want to authenticate a client and require the client to provide an SSL certificate to it,which it verifies against its known certificate authorities or performs additional checks on the client identityif needed (see CREATE USER SSL/TLS Options for details). In that case, Connector/J needs to haveaccess to the client certificate, so it can be sent to the server while establishing new database connections.This is done using the Java keystore files.

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To allow client authentication, the client connecting to the server must have its own set of keys and an SSLcertificate. The client certificate must be signed so that the server can verify it. While you can have theclient certificates signed by official certificate authorities, it is more common to use an intermediate, private,CA certificate to sign client certificates. Such an intermediate CA certificate may be self-signed or signedby a trusted root CA. The requirement is that the server knows a CA certificate that is capable of validatingthe client certificate.

Some MySQL server builds are able to generate SSL keys and certificates for communication encryption,including a certificate and a private key (contained in the client-cert.pem and client-key.pemfiles), which can be used by any client. This SSL certificate is already signed by the self-signed CAcertificate ca.pem, which the server may have already been configured to use.

If you do not want to use the client keys and certificate files generated by the server, you can also generatenew ones using the procedures described in Creating SSL and RSA Certificates and Keys. Notice that,according to the setup of the server, you may have to reuse the already existing CA certificate the server isconfigured to work with to sign the new client certificate, instead of creating a new one.

Once you have the client private key and certificate files you want to use, you need to import them into aJava keystore so that they can be used by the Java SSL library and Connector/J. The following instructionsexplain how to create the keystore file:

• Convert the client key and certificate files to a PKCS #12 archive:

$> openssl pkcs12 -export -in client-cert.pem -inkey client-key.pem \ -name "mysqlclient" -passout pass:mypassword -out client-keystore.p12

• Import the client key and certificate into a Java keystore:

$> keytool -importkeystore -srckeystore client-keystore.p12 -srcstoretype pkcs12 \ -srcstorepass mypassword -destkeystore keystore -deststoretype JKS -deststorepass mypassword

Supply the proper arguments for the command options. If the keystore file does not already exist, a newone will be created; otherwise the certificate will be added to the existing file. Output by keytool lookslike this:

Entry for alias mysqlclient successfully imported.Import command completed: 1 entries successfully imported, 0 entries failed or cancelled

Make sure you remember the password you have chosen. Also, be mindful that the password will haveto be written as plain text in your Connector/J configuration file or application source code.

After the step, you can delete the PKCS #12 archive (client-keystore.p12 in the example).

The next step is to configure Java or Connector/J so that it reads the truststore you just created ormodified. This can be done by using one of the following three methods:

• Using the Java command line arguments:

-Djavax.net.ssl.keyStore=path_to_keystore_file-Djavax.net.ssl.keyStorePassword=mypassword

• Setting the system properties directly in the client code:

System.setProperty("javax.net.ssl.keyStore","path_to_keystore_file"); System.setProperty("javax.net.ssl.keyStorePassword","mypassword");

• Through Connector/J connection properties:

clientCertificateKeyStoreUrl=file:path_to_truststore_file clientCertificateKeyStorePassword=mypassword

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Setting up 2-Way Authentication

Notice that when used together, the connection properties override the values set by the other twomethods. Also, whatever values set with connection properties are used in that connection only, whilevalues set using the system-wide values are used for all connections (unless overridden by the connectionproperties).

With the above setups , all connections established are going to be SSL-encrypted with the client beingauthenticated in the SSL handshake process, and the server can now safely trust the client that isrequesting a connection to it.

Setting up 2-Way Authentication

Apply the steps outlined in both Setting up Server Authentication and Setting up Client Authentication toset up a mutual, two-way authentication process in which the server and the client authenticate each otherbefore establishing a connection.

Although the typical setup described above uses the same CA certificate in both ends for mutualauthentication, it does not have to be the case. The only requirements are that the CA certificateconfigured in the server must be able to validate the client certificate and the CA certificate imported intothe client truststore must be able to validate the server certificate; the two CA certificates used on the twoends can be distinct.

Debugging an SSL Connection

JSSE provides debugging information to stdout when you set the system property -Djavax.net.debug=all. Java then tells you what keystores and truststores are being used, as well aswhat is going on during the SSL handshake and certificate exchange. That will be helpful when you aretrying to debug a failed SSL connection.

5.8 Connecting Using Unix Domain SocketsConnector/J does not natively support connections to MySQL Servers with Unix domain sockets. However,there is provision for using 3rd-party libraries that supply the function via a pluggable socket factory.Such a custom factory should implement the legacy com.mysql.jdbc.SocketFactory interface ofConnector/J. Follow these requirements when you use such a custom socket factory for Unix sockets :

• The MySQL Server must be configured with the system variable --socket, which must contain the filepath of the Unix socket file.

• The fully-qualified class name of the custom factory should be passed to Connector/J via the connectionproperty socketFactory. For example, with the junixsocket library, set:

socketFactory=org.newsclub.net.mysql.AFUNIXDatabaseSocketFactory

You might also need to pass other parameters to the custom factory as connection properties.For example, for the junixsocket library, provide the file path of the socket file with the propertyjunixsocket.file:

junixsocket.file=path_to_socket_file

5.9 Connecting Using Named PipesImportant

For MySQL 8.0.14 and later, 5.7.25 and later, and 5.6.43 and later, minimalpermissions on named pipes are granted to clients that use them to connect to theserver. Connector/J, however, can only use named pipes when granted full access

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Connecting Using PAM Authentication

on them. As a workaround, the MySQL Server that Connector/J wants to connectto must be started with the system variable named_pipe_full_access_group,which specifies a Windows local group containing the user by which the clientapplication JVM (and thus Connector/J) is being executed; see the description fornamed_pipe_full_access_group for more details.

Connector/J also supports access to MySQL using named pipes on Windows platforms with theNamedPipeSocketFactory as a plugin-sockets factory. If you do not use a namedPipePath property,the default of '\\.\pipe\MySQL' is used. If you use the NamedPipeSocketFactory, the host nameand port number values in the JDBC URL are ignored. To enable this feature, set the socketFactoryproperty:

socketFactory=com.mysql.cj.protocol.NamedPipeSocketFactory

Set this property, as well as the path of the named pipe, with the following connection URL:

jdbc:mysql:///test?socketFactory=com.mysql.cj.protocol.NamedPipeSocketFactory&namedPipePath=\\.\pipe\MySQL57

To create your own socket factories, follow the sample code incom.mysql.cj.protocol.NamedPipeSocketFactory orcom.mysql.cj.protocol.StandardSocketFactory.

An alternate approach is to use the following two properties in connection URLs for establishing namedpipe connections on Windows platforms:

• (protocol=pipe) for named pipes (default value for the property is tcp).

• (path=path_to_pipe) for path of named pipes. Default value for the path is \\.\pipe\MySQL.

The “address-equals” or “key-value” form of host specification (see Single host [18] for details) greatlysimplifies the URL for a named pipe connection on Windows. For example, to use the default named pipeof “\\.\pipe\MySQL,” just specify:

jdbc:mysql://address=(protocol=pipe)/test

To use the custom named pipe of “\\.\pipe\MySQL57” :

jdbc:mysql://address=(protocol=pipe)(path=\\.\pipe\MySQL57)/test

With (protocol=pipe), the NamedPipeSocketFactory is automatically selected.

Named pipes only work when connecting to a MySQL server on the same physical machine where theJDBC driver is running. In simple performance tests, named pipe access is between 30%-50% faster thanthe standard TCP/IP access. However, this varies per system, and named pipes are slower than TCP/IP inmany Windows configurations.

5.10 Connecting Using PAM AuthenticationJava applications using Connector/J 5.1.21 and higher can connect to MySQL servers that use thepluggable authentication module (PAM) authentication scheme.

For PAM authentication to work, you must have the following:

• A MySQL server that supports PAM authentication. See PAM Pluggable Authentication for moreinformation. Connector/J implements the same cleartext authentication method as in Client-SideCleartext Pluggable Authentication.

• SSL capability, as explained in Section 5.7, “Connecting Securely Using SSL”. Because the PAMauthentication scheme sends the original password to the server, the connection to the server must beencrypted.

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/pam-pluggable-authentication.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/cleartext-pluggable-authentication.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/cleartext-pluggable-authentication.html

Source/Replica Using Replication with ReplicationConnection

PAM authentication support is enabled by default in Connector/J 5.1.21 and up, so no extra configuration isneeded.

To disable the PAM authentication feature, specify mysql_clear_password (the method) orcom.mysql.jdbc.authentication.MysqlClearPasswordPlugin (the class name) in the comma-separated list of arguments for the disabledAuthenticationPlugins connection option. SeeSection 5.3, “Configuration Properties for Connector/J” for details about that connection option.

5.11 Source/Replica Using Replication with ReplicationConnection

See Section 8.3, “Configuring Source/Replica Replication with Connector/J” for details on the topic.

5.12 Mapping MySQL Error Numbers to JDBC SQLState Codes

The table below provides a mapping of the MySQL error numbers to JDBC SQLState values.

Table 5.4 Mapping of MySQL Error Numbers to SQLStates

MySQLErrorNumber

MySQL Error Name Legacy(X/Open)SQLState

SQLStandardSQLState

1022 ER_DUP_KEY 23000 23000

1037 ER_OUTOFMEMORY S1001 HY001

1038 ER_OUT_OF_SORTMEMORY S1001 HY001

1040 ER_CON_COUNT_ERROR 08004 08004

1042 ER_BAD_HOST_ERROR 08004 08S01

1043 ER_HANDSHAKE_ERROR 08004 08S01

1044 ER_DBACCESS_DENIED_ERROR 42000 42000

1045 ER_ACCESS_DENIED_ERROR 28000 28000

1046 ER_NO_DB_ERROR 3D000 3D000

1047 ER_UNKNOWN_COM_ERROR 08S01 08S01

1048 ER_BAD_NULL_ERROR 23000 23000

1049 ER_BAD_DB_ERROR 42000 42000

1050 ER_TABLE_EXISTS_ERROR 42S01 42S01

1051 ER_BAD_TABLE_ERROR 42S02 42S02

1052 ER_NON_UNIQ_ERROR 23000 23000

1053 ER_SERVER_SHUTDOWN 08S01 08S01

1054 ER_BAD_FIELD_ERROR S0022 42S22

1055 ER_WRONG_FIELD_WITH_GROUP S1009 42000

1056 ER_WRONG_GROUP_FIELD S1009 42000

1057 ER_WRONG_SUM_SELECT S1009 42000

1058 ER_WRONG_VALUE_COUNT 21S01 21S01

1059 ER_TOO_LONG_IDENT S1009 42000

1060 ER_DUP_FIELDNAME S1009 42S21

1061 ER_DUP_KEYNAME S1009 42000

67

Mapping MySQL Error Numbers to JDBC SQLState Codes

MySQLErrorNumber


SQLStandardSQLState

1062 ER_DUP_ENTRY S1009 23000

1063 ER_WRONG_FIELD_SPEC S1009 42000

1064 ER_PARSE_ERROR 42000 42000

1065 ER_EMPTY_QUERY 42000 42000

1066 ER_NONUNIQ_TABLE S1009 42000

1067 ER_INVALID_DEFAULT S1009 42000

1068 ER_MULTIPLE_PRI_KEY S1009 42000

1069 ER_TOO_MANY_KEYS S1009 42000

1070 ER_TOO_MANY_KEY_PARTS S1009 42000

1071 ER_TOO_LONG_KEY S1009 42000

1072 ER_KEY_COLUMN_DOES_NOT_EXITS S1009 42000

1073 ER_BLOB_USED_AS_KEY S1009 42000

1074 ER_TOO_BIG_FIELDLENGTH S1009 42000

1075 ER_WRONG_AUTO_KEY S1009 42000

1080 ER_FORCING_CLOSE 08S01 08S01

1081 ER_IPSOCK_ERROR 08S01 08S01

1082 ER_NO_SUCH_INDEX S1009 42S12

1083 ER_WRONG_FIELD_TERMINATORS S1009 42000

1084 ER_BLOBS_AND_NO_TERMINATED S1009 42000

1090 ER_CANT_REMOVE_ALL_FIELDS 42000 42000

1091 ER_CANT_DROP_FIELD_OR_KEY 42000 42000

1101 ER_BLOB_CANT_HAVE_DEFAULT 42000 42000

1102 ER_WRONG_DB_NAME 42000 42000

1103 ER_WRONG_TABLE_NAME 42000 42000

1104 ER_TOO_BIG_SELECT 42000 42000

1106 ER_UNKNOWN_PROCEDURE 42000 42000

1107 ER_WRONG_PARAMCOUNT_TO_PROCEDURE 42000 42000

1109 ER_UNKNOWN_TABLE 42S02 42S02

1110 ER_FIELD_SPECIFIED_TWICE 42000 42000

1112 ER_UNSUPPORTED_EXTENSION 42000 42000

1113 ER_TABLE_MUST_HAVE_COLUMNS 42000 42000

1115 ER_UNKNOWN_CHARACTER_SET 42000 42000

1118 ER_TOO_BIG_ROWSIZE 42000 42000

1120 ER_WRONG_OUTER_JOIN 42000 42000

1121 ER_NULL_COLUMN_IN_INDEX 42000 42000

1129 ER_HOST_IS_BLOCKED 08004 HY000

68


MySQLErrorNumber


SQLStandardSQLState

1130 ER_HOST_NOT_PRIVILEGED 08004 HY000

1131 ER_PASSWORD_ANONYMOUS_USER 42000 42000

1132 ER_PASSWORD_NOT_ALLOWED 42000 42000

1133 ER_PASSWORD_NO_MATCH 42000 42000

1136 ER_WRONG_VALUE_COUNT_ON_ROW 21S01 21S01

1138 ER_INVALID_USE_OF_NULL S1000 42000

1139 ER_REGEXP_ERROR 42000 42000

1140 ER_MIX_OF_GROUP_FUNC_AND_FIELDS 42000 42000

1141 ER_NONEXISTING_GRANT 42000 42000

1142 ER_TABLEACCESS_DENIED_ERROR 42000 42000

1143 ER_COLUMNACCESS_DENIED_ERROR 42000 42000

1144 ER_ILLEGAL_GRANT_FOR_TABLE 42000 42000

1145 ER_GRANT_WRONG_HOST_OR_USER 42000 42000

1146 ER_NO_SUCH_TABLE 42S02 42S02

1147 ER_NONEXISTING_TABLE_GRANT 42000 42000

1148 ER_NOT_ALLOWED_COMMAND 42000 42000

1149 ER_SYNTAX_ERROR 42000 42000

1152 ER_ABORTING_CONNECTION 08S01 08S01

1153 ER_NET_PACKET_TOO_LARGE 08S01 08S01

1154 ER_NET_READ_ERROR_FROM_PIPE 08S01 08S01

1155 ER_NET_FCNTL_ERROR 08S01 08S01

1156 ER_NET_PACKETS_OUT_OF_ORDER 08S01 08S01

1157 ER_NET_UNCOMPRESS_ERROR 08S01 08S01

1158 ER_NET_READ_ERROR 08S01 08S01

1159 ER_NET_READ_INTERRUPTED 08S01 08S01

1160 ER_NET_ERROR_ON_WRITE 08S01 08S01

1161 ER_NET_WRITE_INTERRUPTED 08S01 08S01

1162 ER_TOO_LONG_STRING 42000 42000

1163 ER_TABLE_CANT_HANDLE_BLOB 42000 42000

1164 ER_TABLE_CANT_HANDLE_AUTO_INCREMENT 42000 42000

1166 ER_WRONG_COLUMN_NAME 42000 42000

1167 ER_WRONG_KEY_COLUMN 42000 42000

1169 ER_DUP_UNIQUE 23000 23000

1170 ER_BLOB_KEY_WITHOUT_LENGTH 42000 42000

1171 ER_PRIMARY_CANT_HAVE_NULL 42000 42000

1172 ER_TOO_MANY_ROWS 42000 42000

69


MySQLErrorNumber


SQLStandardSQLState

1173 ER_REQUIRES_PRIMARY_KEY 42000 42000

1176 ER_KEY_DOES_NOT_EXITS 42000 42000

1177 ER_CHECK_NO_SUCH_TABLE 42000 42000

1178 ER_CHECK_NOT_IMPLEMENTED 42000 42000

1179 ER_CANT_DO_THIS_DURING_AN_TRANSACTION 25000 25000

1184 ER_NEW_ABORTING_CONNECTION 08S01 08S01

1189 ER_MASTER_NET_READ 08S01 08S01

1190 ER_MASTER_NET_WRITE 08S01 08S01

1203 ER_TOO_MANY_USER_CONNECTIONS 42000 42000

1205 ER_LOCK_WAIT_TIMEOUT 40001 40001

1207 ER_READ_ONLY_TRANSACTION 25000 25000

1211 ER_NO_PERMISSION_TO_CREATE_USER 42000 42000

1213 ER_LOCK_DEADLOCK 40001 40001

1216 ER_NO_REFERENCED_ROW 23000 23000

1217 ER_ROW_IS_REFERENCED 23000 23000

1218 ER_CONNECT_TO_MASTER 08S01 08S01

1222 ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT 21000 21000

1226 ER_USER_LIMIT_REACHED 42000 42000

1227 ER_SPECIFIC_ACCESS_DENIED_ERROR 42000 42000

1230 ER_NO_DEFAULT 42000 42000

1231 ER_WRONG_VALUE_FOR_VAR 42000 42000

1232 ER_WRONG_TYPE_FOR_VAR 42000 42000

1234 ER_CANT_USE_OPTION_HERE 42000 42000

1235 ER_NOT_SUPPORTED_YET 42000 42000

1239 ER_WRONG_FK_DEF 42000 42000

1241 ER_OPERAND_COLUMNS 21000 21000

1242 ER_SUBQUERY_NO_1_ROW 21000 21000

1247 ER_ILLEGAL_REFERENCE 42S22 42S22

1248 ER_DERIVED_MUST_HAVE_ALIAS 42000 42000

1249 ER_SELECT_REDUCED 01000 01000

1250 ER_TABLENAME_NOT_ALLOWED_HERE 42000 42000

1251 ER_NOT_SUPPORTED_AUTH_MODE 08004 08004

1252 ER_SPATIAL_CANT_HAVE_NULL 42000 42000

1253 ER_COLLATION_CHARSET_MISMATCH 42000 42000

1261 ER_WARN_TOO_FEW_RECORDS 01000 01000

1262 ER_WARN_TOO_MANY_RECORDS 01000 01000

70


MySQLErrorNumber


SQLStandardSQLState

1263 ER_WARN_NULL_TO_NOTNULL S1000 01000

1264 ER_WARN_DATA_OUT_OF_RANGE 01000 01000

1265 ER_WARN_DATA_TRUNCATED 01000 01000

1280 ER_WRONG_NAME_FOR_INDEX 42000 42000

1281 ER_WRONG_NAME_FOR_CATALOG 42000 42000

1286 ER_UNKNOWN_STORAGE_ENGINE 42000 42000

1292 ER_TRUNCATED_WRONG_VALUE 22007 22007

1303 ER_SP_NO_RECURSIVE_CREATE S1000 2F003

1304 ER_SP_ALREADY_EXISTS 42000 42000

1305 ER_SP_DOES_NOT_EXIST 42000 42000

1308 ER_SP_LILABEL_MISMATCH 42000 42000

1309 ER_SP_LABEL_REDEFINE 42000 42000

1310 ER_SP_LABEL_MISMATCH 42000 42000

1311 ER_SP_UNINIT_VAR 01000 01000

1312 ER_SP_BADSELECT 0A000 0A000

1313 ER_SP_BADRETURN 42000 42000

1314 ER_SP_BADSTATEMENT 0A000 0A000

1315 ER_UPDATE_LOG_DEPRECATED_IGNORED 42000 42000

1316 ER_UPDATE_LOG_DEPRECATED_TRANSLATED 42000 42000

1317 ER_QUERY_INTERRUPTED S1000 70100

1318 ER_SP_WRONG_NO_OF_ARGS 42000 42000

1319 ER_SP_COND_MISMATCH 42000 42000

1320 ER_SP_NORETURN 42000 42000

1321 ER_SP_NORETURNEND S1000 2F005

1322 ER_SP_BAD_CURSOR_QUERY 42000 42000

1323 ER_SP_BAD_CURSOR_SELECT 42000 42000

1324 ER_SP_CURSOR_MISMATCH 42000 42000

1325 ER_SP_CURSOR_ALREADY_OPEN 24000 24000

1326 ER_SP_CURSOR_NOT_OPEN 24000 24000

1327 ER_SP_UNDECLARED_VAR 42000 42000

1329 ER_SP_FETCH_NO_DATA S1000 02000

1330 ER_SP_DUP_PARAM 42000 42000

1331 ER_SP_DUP_VAR 42000 42000

1332 ER_SP_DUP_COND 42000 42000

1333 ER_SP_DUP_CURS 42000 42000

1335 ER_SP_SUBSELECT_NYI 0A000 0A000

71


MySQLErrorNumber


SQLStandardSQLState

1336 ER_STMT_NOT_ALLOWED_IN_SF_OR_TRG 0A000 0A000

1337 ER_SP_VARCOND_AFTER_CURSHNDLR 42000 42000

1338 ER_SP_CURSOR_AFTER_HANDLER 42000 42000

1339 ER_SP_CASE_NOT_FOUND S1000 20000

1365 ER_DIVISION_BY_ZERO 22012 22012

1367 ER_ILLEGAL_VALUE_FOR_TYPE 22007 22007

1370 ER_PROCACCESS_DENIED_ERROR 42000 42000

1397 ER_XAER_NOTA S1000 XAE04

1398 ER_XAER_INVAL S1000 XAE05

1399 ER_XAER_RMFAIL S1000 XAE07

1400 ER_XAER_OUTSIDE S1000 XAE09

1401 ER_XA_RMERR S1000 XAE03

1402 ER_XA_RBROLLBACK S1000 XA100

1403 ER_NONEXISTING_PROC_GRANT 42000 42000

1406 ER_DATA_TOO_LONG 22001 22001

1407 ER_SP_BAD_SQLSTATE 42000 42000

1410 ER_CANT_CREATE_USER_WITH_GRANT 42000 42000

1413 ER_SP_DUP_HANDLER 42000 42000

1414 ER_SP_NOT_VAR_ARG 42000 42000

1415 ER_SP_NO_RETSET 0A000 0A000

1416 ER_CANT_CREATE_GEOMETRY_OBJECT 22003 22003

1425 ER_TOO_BIG_SCALE 42000 42000

1426 ER_TOO_BIG_PRECISION 42000 42000

1427 ER_M_BIGGER_THAN_D 42000 42000

1437 ER_TOO_LONG_BODY 42000 42000

1439 ER_TOO_BIG_DISPLAYWIDTH 42000 42000

1440 ER_XAER_DUPID S1000 XAE08

1441 ER_DATETIME_FUNCTION_OVERFLOW 22008 22008

1451 ER_ROW_IS_REFERENCED_2 23000 23000

1452 ER_NO_REFERENCED_ROW_2 23000 23000

1453 ER_SP_BAD_VAR_SHADOW 42000 42000

1458 ER_SP_WRONG_NAME 42000 42000

1460 ER_SP_NO_AGGREGATE 42000 42000

1461 ER_MAX_PREPARED_STMT_COUNT_REACHED 42000 42000

1463 ER_NON_GROUPING_FIELD_USED 42000 42000

1557 ER_FOREIGN_DUPLICATE_KEY 23000 23000

72


MySQLErrorNumber


SQLStandardSQLState

1568 ER_CANT_CHANGE_TX_ISOLATION S1000 25001

1582 ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT 42000 42000

1583 ER_WRONG_PARAMETERS_TO_NATIVE_FCT 42000 42000

1584 ER_WRONG_PARAMETERS_TO_STORED_FCT 42000 42000

1586 ER_DUP_ENTRY_WITH_KEY_NAME 23000 23000

1613 ER_XA_RBTIMEOUT S1000 XA106

1614 ER_XA_RBDEADLOCK S1000 XA102

1630 ER_FUNC_INEXISTENT_NAME_COLLISION 42000 42000

1641 ER_DUP_SIGNAL_SET 42000 42000

1642 ER_SIGNAL_WARN 01000 01000

1643 ER_SIGNAL_NOT_FOUND S1000 02000

1645 ER_RESIGNAL_WITHOUT_ACTIVE_HANDLER S1000 0K000

1687 ER_SPATIAL_MUST_HAVE_GEOM_COL 42000 42000

1690 ER_DATA_OUT_OF_RANGE 22003 22003

1698 ER_ACCESS_DENIED_NO_PASSWORD_ERROR 28000 28000

1701 ER_TRUNCATE_ILLEGAL_FK 42000 42000

1758 ER_DA_INVALID_CONDITION_NUMBER 35000 35000

1761 ER_FOREIGN_DUPLICATE_KEY_WITH_CHILD_INFO 23000 23000

1762 ER_FOREIGN_DUPLICATE_KEY_WITHOUT_CHILD_INFO 23000 23000

1792 ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION S1000 25006

1845 ER_ALTER_OPERATION_NOT_SUPPORTED 0A000 0A000

1846 ER_ALTER_OPERATION_NOT_SUPPORTED_REASON 0A000 0A000

1859 ER_DUP_UNKNOWN_IN_INDEX 23000 23000

1873 ER_ACCESS_DENIED_CHANGE_USER_ERROR 28000 28000

1887 ER_GET_STACKED_DA_WITHOUT_ACTIVE_HANDLER S1000 0Z002

1903 ER_INVALID_ARGUMENT_FOR_LOGARITHM S1000 2201E

73

Chapter 6 JDBC Concepts

Table of Contents6.1 Connecting to MySQL Using the JDBC DriverManager Interface ............................................... 756.2 Using JDBC Statement Objects to Execute SQL ....................................................................... 766.3 Using JDBC CallableStatements to Execute Stored Procedures ............................................. 776.4 Retrieving AUTO_INCREMENT Column Values through JDBC ........................................................ 80

This section provides some general JDBC background.

6.1 Connecting to MySQL Using the JDBC DriverManager Interface

When you are using JDBC outside of an application server, the DriverManager class manages theestablishment of connections.

Specify to the DriverManager which JDBC drivers to try to make Connections with. The easiest wayto do this is to use Class.forName() on the class that implements the java.sql.Driver interface.With MySQL Connector/J, the name of this class is com.mysql.jdbc.Driver. With this method, youcould use an external configuration file to supply the driver class name and driver parameters to use whenconnecting to a database.

The following section of Java code shows how you might register MySQL Connector/J from the main()method of your application. If testing this code, first read the installation section at Chapter 3, Connector/JInstallation, to make sure you have connector installed correctly and the CLASSPATH set up. Also, ensurethat MySQL is configured to accept external TCP/IP connections.

import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;

// Notice, do not import com.mysql.jdbc.*// or you will have problems!

public class LoadDriver { public static void main(String[] args) { try { // The newInstance() call is a work around for some // broken Java implementations

Class.forName("com.mysql.jdbc.Driver").newInstance(); } catch (Exception ex) { // handle the error } }}

After the driver has been registered with the DriverManager, you can obtain a Connection instancethat is connected to a particular database by calling DriverManager.getConnection():

Example 6.1 Connector/J: Obtaining a connection from the DriverManager

If you have not already done so, please review the portion of Section 6.1, “Connecting to MySQL Using theJDBC DriverManager Interface” above before working with the example below.

75

Using JDBC Statement Objects to Execute SQL

This example shows how you can obtain a Connection instance from the DriverManager. There area few different signatures for the getConnection() method. Consult the API documentation that comeswith your JDK for more specific information on how to use them.

import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;

Connection conn = null;...try { conn = DriverManager.getConnection("jdbc:mysql://localhost/test?" + "user=minty&password=greatsqldb");

// Do something with the Connection

...} catch (SQLException ex) { // handle any errors System.out.println("SQLException: " + ex.getMessage()); System.out.println("SQLState: " + ex.getSQLState()); System.out.println("VendorError: " + ex.getErrorCode());}

Once a Connection is established, it can be used to create Statement and PreparedStatementobjects, as well as retrieve metadata about the database. This is explained in the following sections.

6.2 Using JDBC Statement Objects to Execute SQL

Statement objects allow you to execute basic SQL queries and retrieve the results through theResultSet class, which is described later.

To create a Statement instance, you call the createStatement() method on theConnection object you have retrieved using one of the DriverManager.getConnection() orDataSource.getConnection() methods described earlier.

Once you have a Statement instance, you can execute a SELECT query by calling theexecuteQuery(String) method with the SQL you want to use.

To update data in the database, use the executeUpdate(String SQL) method. This method returnsthe number of rows matched by the update statement, not the number of rows that were modified.

If you do not know ahead of time whether the SQL statement will be a SELECT or an UPDATE/INSERT,then you can use the execute(String SQL) method. This method will return true if the SQL querywas a SELECT, or false if it was an UPDATE, INSERT, or DELETE statement. If the statement was aSELECT query, you can retrieve the results by calling the getResultSet() method. If the statementwas an UPDATE, INSERT, or DELETE statement, you can retrieve the affected rows count by callinggetUpdateCount() on the Statement instance.

Example 6.2 Connector/J: Using java.sql.Statement to execute a SELECT query

import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;import java.sql.ResultSet;

// assume that conn is an already created JDBC connection (see previous examples)

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/insert.html




https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/delete.html





Using JDBC CallableStatements to Execute Stored Procedures

Statement stmt = null;ResultSet rs = null;

try { stmt = conn.createStatement(); rs = stmt.executeQuery("SELECT foo FROM bar");

// or alternatively, if you don't know ahead of time that // the query will be a SELECT...

if (stmt.execute("SELECT foo FROM bar")) { rs = stmt.getResultSet(); }

// Now do something with the ResultSet ....}catch (SQLException ex){ // handle any errors System.out.println("SQLException: " + ex.getMessage()); System.out.println("SQLState: " + ex.getSQLState()); System.out.println("VendorError: " + ex.getErrorCode());}finally { // it is a good idea to release // resources in a finally{} block // in reverse-order of their creation // if they are no-longer needed

if (rs != null) { try { rs.close(); } catch (SQLException sqlEx) { } // ignore

rs = null; }

if (stmt != null) { try { stmt.close(); } catch (SQLException sqlEx) { } // ignore

stmt = null; }}

6.3 Using JDBC CallableStatements to Execute StoredProcedures

Starting with MySQL server version 5.0 when used with Connector/J 3.1.1 or newer, thejava.sql.CallableStatement interface is fully implemented with the exception of thegetParameterMetaData() method.

For more information on MySQL stored procedures, please refer to Using Stored Routines.

Connector/J exposes stored procedure functionality through JDBC's CallableStatement interface.

Note

Current versions of MySQL server do not return enough information for the JDBCdriver to provide result set metadata for callable statements. This means that whenusing CallableStatement, ResultSetMetaData may return NULL.

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The following example shows a stored procedure that returns the value of inOutParam incremented by 1,and the string passed in using inputParam as a ResultSet:

Example 6.3 Connector/J: Calling Stored Procedures

CREATE PROCEDURE demoSp(IN inputParam VARCHAR(255), \ INOUT inOutParam INT)BEGIN DECLARE z INT; SET z = inOutParam + 1; SET inOutParam = z;

SELECT inputParam;

SELECT CONCAT('zyxw', inputParam);END

To use the demoSp procedure with Connector/J, follow these steps:

1. Prepare the callable statement by using Connection.prepareCall().

Notice that you have to use JDBC escape syntax, and that the parentheses surrounding the parameterplaceholders are not optional:

Example 6.4 Connector/J: Using Connection.prepareCall()

import java.sql.CallableStatement;

...

// // Prepare a call to the stored procedure 'demoSp' // with two parameters // // Notice the use of JDBC-escape syntax ({call ...}) //

CallableStatement cStmt = conn.prepareCall("{call demoSp(?, ?)}");

cStmt.setString(1, "abcdefg");

Note

Connection.prepareCall() is an expensive method, due to the metadataretrieval that the driver performs to support output parameters. For performancereasons, minimize unnecessary calls to Connection.prepareCall() byreusing CallableStatement instances in your code.

2. Register the output parameters (if any exist)

To retrieve the values of output parameters (parameters specified as OUT or INOUT when you createdthe stored procedure), JDBC requires that they be specified before statement execution using thevarious registerOutputParameter() methods in the CallableStatement interface:

Example 6.5 Connector/J: Registering output parameters

import java.sql.Types;...//// Connector/J supports both named and indexed// output parameters. You can register output

78


// parameters using either method, as well// as retrieve output parameters using either// method, regardless of what method was// used to register them.//// The following examples show how to use// the various methods of registering// output parameters (you should of course// use only one registration per parameter).//

//// Registers the second parameter as output, and// uses the type 'INTEGER' for values returned from// getObject()//

cStmt.registerOutParameter(2, Types.INTEGER);

//// Registers the named parameter 'inOutParam', and// uses the type 'INTEGER' for values returned from// getObject()//

cStmt.registerOutParameter("inOutParam", Types.INTEGER);...

3. Set the input parameters (if any exist)

Input and in/out parameters are set as for PreparedStatement objects. However,CallableStatement also supports setting parameters by name:

Example 6.6 Connector/J: Setting CallableStatement input parameters

...

// // Set a parameter by index //

cStmt.setString(1, "abcdefg");

// // Alternatively, set a parameter using // the parameter name //

cStmt.setString("inputParam", "abcdefg");

// // Set the 'in/out' parameter using an index //

cStmt.setInt(2, 1);

// // Alternatively, set the 'in/out' parameter // by name //

cStmt.setInt("inOutParam", 1);

...

4. Execute the CallableStatement, and retrieve any result sets or output parameters.

79

Retrieving AUTO_INCREMENT Column Values through JDBC

Although CallableStatement supports calling any of the Statement execute methods(executeUpdate(), executeQuery() or execute()), the most flexible method to call isexecute(), as you do not need to know ahead of time if the stored procedure returns result sets:

Example 6.7 Connector/J: Retrieving results and output parameter values

...

boolean hadResults = cStmt.execute();

// // Process all returned result sets //

while (hadResults) { ResultSet rs = cStmt.getResultSet();

// process result set ...

hadResults = cStmt.getMoreResults(); }

// // Retrieve output parameters // // Connector/J supports both index-based and // name-based retrieval //

int outputValue = cStmt.getInt(2); // index-based

outputValue = cStmt.getInt("inOutParam"); // name-based

...

6.4 Retrieving AUTO_INCREMENT Column Values through JDBCBefore version 3.0 of the JDBC API, there was no standard way of retrieving key values from databasesthat supported auto increment or identity columns. With older JDBC drivers for MySQL, you couldalways use a MySQL-specific method on the Statement interface, or issue the query SELECTLAST_INSERT_ID() after issuing an INSERT to a table that had an AUTO_INCREMENT key. Using theMySQL-specific method call isn't portable, and issuing a SELECT to get the AUTO_INCREMENT key's valuerequires another round-trip to the database, which isn't as efficient as possible. The following code snippetsdemonstrate the three different ways to retrieve AUTO_INCREMENT values. First, we demonstrate the useof the new JDBC 3.0 method getGeneratedKeys() which is now the preferred method to use if youneed to retrieve AUTO_INCREMENT keys and have access to JDBC 3.0. The second example shows howyou can retrieve the same value using a standard SELECT LAST_INSERT_ID() query. The final exampleshows how updatable result sets can retrieve the AUTO_INCREMENT value when using the insertRow()method.

Example 6.8 Connector/J: Retrieving AUTO_INCREMENT column values usingStatement.getGeneratedKeys()


try {

// // Create a Statement instance that we can use for

80




// 'normal' result sets assuming you have a // Connection 'conn' to a MySQL database already // available

stmt = conn.createStatement();

// // Issue the DDL queries for the table for this example //

stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial"); stmt.executeUpdate( "CREATE TABLE autoIncTutorial (" + "priKey INT NOT NULL AUTO_INCREMENT, " + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

// // Insert one row that will generate an AUTO INCREMENT // key in the 'priKey' field //

stmt.executeUpdate( "INSERT INTO autoIncTutorial (dataField) " + "values ('Can I Get the Auto Increment Field?')", Statement.RETURN_GENERATED_KEYS);

// // Example of using Statement.getGeneratedKeys() // to retrieve the value of an auto-increment // value //

int autoIncKeyFromApi = -1;

rs = stmt.getGeneratedKeys();

if (rs.next()) { autoIncKeyFromApi = rs.getInt(1); } else {

// throw an exception from here }

System.out.println("Key returned from getGeneratedKeys():" + autoIncKeyFromApi);} finally {

if (rs != null) { try { rs.close(); } catch (SQLException ex) { // ignore } }

if (stmt != null) { try { stmt.close(); } catch (SQLException ex) { // ignore } }}

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Example 6.9 Connector/J: Retrieving AUTO_INCREMENT column values using SELECTLAST_INSERT_ID()


try {

// // Create a Statement instance that we can use for // 'normal' result sets.




// // Insert one row that will generate an AUTO INCREMENT // key in the 'priKey' field //

stmt.executeUpdate( "INSERT INTO autoIncTutorial (dataField) " + "values ('Can I Get the Auto Increment Field?')");

// // Use the MySQL LAST_INSERT_ID() // function to do the same thing as getGeneratedKeys() //

int autoIncKeyFromFunc = -1; rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

if (rs.next()) { autoIncKeyFromFunc = rs.getInt(1); } else { // throw an exception from here }

System.out.println("Key returned from " + "'SELECT LAST_INSERT_ID()': " + autoIncKeyFromFunc);

} finally {


if (stmt != null) { try { stmt.close(); } catch (SQLException ex) { // ignore }

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}}

Example 6.10 Connector/J: Retrieving AUTO_INCREMENT column values in Updatable ResultSets


try {

// // Create a Statement instance that we can use for // 'normal' result sets as well as an 'updatable' // one, assuming you have a Connection 'conn' to // a MySQL database already available //

stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY, java.sql.ResultSet.CONCUR_UPDATABLE);



// // Example of retrieving an AUTO INCREMENT key // from an updatable result set //

rs = stmt.executeQuery("SELECT priKey, dataField " + "FROM autoIncTutorial");

rs.moveToInsertRow();

rs.updateString("dataField", "AUTO INCREMENT here?"); rs.insertRow();

// // the driver adds rows at the end //

rs.last();

// // We should now be on the row we just inserted //

int autoIncKeyFromRS = rs.getInt("priKey");

System.out.println("Key returned for inserted row: " + autoIncKeyFromRS);

} finally {


83


if (stmt != null) { try { stmt.close(); } catch (SQLException ex) { // ignore } }}

Running the preceding example code should produce the following output:

Key returned from getGeneratedKeys(): 1Key returned from SELECT LAST_INSERT_ID(): 1Key returned for inserted row: 1

At times, it can be tricky to use the SELECT LAST_INSERT_ID() query, as that function's value is scopedto a connection. So, if some other query happens on the same connection, the value is overwritten. On theother hand, the getGeneratedKeys() method is scoped by the Statement instance, so it can be usedeven if other queries happen on the same connection, but not on the same Statement instance.

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Chapter 7 Connection Pooling with Connector/JConnection pooling is a technique of creating and managing a pool of connections that are ready for useby any thread that needs them. Connection pooling can greatly increase the performance of your Javaapplication, while reducing overall resource usage.

How Connection Pooling Works

Most applications only need a thread to have access to a JDBC connection when they are activelyprocessing a transaction, which often takes only milliseconds to complete. When not processing atransaction, the connection sits idle. Connection pooling enables the idle connection to be used by someother thread to do useful work.

In practice, when a thread needs to do work against a MySQL or other database with JDBC, it requests aconnection from the pool. When the thread is finished using the connection, it returns it to the pool, so thatit can be used by any other threads.

When the connection is loaned out from the pool, it is used exclusively by the thread thatrequested it. From a programming point of view, it is the same as if your thread calledDriverManager.getConnection() every time it needed a JDBC connection. With connection pooling,your thread may end up using either a new connection or an already-existing connection.

Benefits of Connection Pooling

The main benefits to connection pooling are:

• Reduced connection creation time.

Although this is not usually an issue with the quick connection setup that MySQL offers compared toother databases, creating new JDBC connections still incurs networking and JDBC driver overhead thatwill be avoided if connections are recycled.

• Simplified programming model.

When using connection pooling, each individual thread can act as though it has created its own JDBCconnection, allowing you to use straightforward JDBC programming techniques.

• Controlled resource usage.

If you create a new connection every time a thread needs one rather than using connection pooling,your application's resource usage can be wasteful, and it could lead to unpredictable behaviors for yourapplication when it is under a heavy load.

Using Connection Pooling with Connector/J

The concept of connection pooling in JDBC has been standardized through the JDBC 2.0 Optionalinterfaces, and all major application servers have implementations of these APIs that work with MySQLConnector/J.

Generally, you configure a connection pool in your application server configuration files, and access itthrough the Java Naming and Directory Interface (JNDI). The following code shows how you might use aconnection pool from an application deployed in a J2EE application server:

Example 7.1 Connector/J: Using a connection pool with a J2EE application server

import java.sql.Connection;import java.sql.SQLException;import java.sql.Statement;

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/glossary.html#glos_transaction

Using Connection Pooling with Connector/J

import javax.naming.InitialContext;import javax.sql.DataSource;

public class MyServletJspOrEjb {

public void doSomething() throws Exception { /* * Create a JNDI Initial context to be able to * lookup the DataSource * * In production-level code, this should be cached as * an instance or static variable, as it can * be quite expensive to create a JNDI context. * * Note: This code only works when you are using servlets * or EJBs in a J2EE application server. If you are * using connection pooling in standalone Java code, you * will have to create/configure datasources using whatever * mechanisms your particular connection pooling library * provides. */

InitialContext ctx = new InitialContext();

/* * Lookup the DataSource, which will be backed by a pool * that the application server provides. DataSource instances * are also a good candidate for caching as an instance * variable, as JNDI lookups can be expensive as well. */

DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/MySQLDB");

/* * The following code is what would actually be in your * Servlet, JSP or EJB 'service' method...where you need * to work with a JDBC connection. */

Connection conn = null; Statement stmt = null;

try { conn = ds.getConnection();

/* * Now, use normal JDBC programming to work with * MySQL, making sure to close each resource when you're * finished with it, which permits the connection pool * resources to be recovered as quickly as possible */

stmt = conn.createStatement(); stmt.execute("SOME SQL QUERY");

stmt.close(); stmt = null;

conn.close(); conn = null; } finally { /* * close any jdbc instances here that weren't * explicitly closed during normal code path, so

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Sizing the Connection Pool

* that we don't 'leak' resources... */

if (stmt != null) { try { stmt.close(); } catch (sqlexception sqlex) { // ignore, as we can't do anything about it here }

stmt = null; }

if (conn != null) { try { conn.close(); } catch (sqlexception sqlex) { // ignore, as we can't do anything about it here }

conn = null; } } }}

As shown in the example above, after obtaining the JNDI InitialContext, and looking up theDataSource, the rest of the code follows familiar JDBC conventions.

When using connection pooling, always make sure that connections, and anything created by them(such as statements or result sets) are closed. This rule applies no matter what happens in your code(exceptions, flow-of-control, and so forth). When these objects are closed, they can be re-used; otherwise,they will be stranded, which means that the MySQL server resources they represent (such as buffers,locks, or sockets) are tied up for some time, or in the worst case can be tied up forever.

Sizing the Connection Pool

Each connection to MySQL has overhead (memory, CPU, context switches, and so forth) on both the clientand server side. Every connection limits how many resources there are available to your application aswell as the MySQL server. Many of these resources will be used whether or not the connection is actuallydoing any useful work! Connection pools can be tuned to maximize performance, while keeping resourceutilization below the point where your application will start to fail rather than just run slower.

The optimal size for the connection pool depends on anticipated load and average database transactiontime. In practice, the optimal connection pool size can be smaller than you might expect. If you takeOracle's Java Petstore blueprint application for example, a connection pool of 15-20 connections can servea relatively moderate load (600 concurrent users) using MySQL and Tomcat with acceptable responsetimes.

To correctly size a connection pool for your application, create load test scripts with tools such as ApacheJMeter or The Grinder, and load test your application.

An easy way to determine a starting point is to configure your connection pool's maximum number ofconnections to be unbounded, run a load test, and measure the largest amount of concurrently usedconnections. You can then work backward from there to determine what values of minimum and maximumpooled connections give the best performance for your particular application.

Validating Connections

MySQL Connector/J can validate the connection by executing a lightweight ping against a server. In thecase of load-balanced connections, this is performed against all active pooled internal connections that are

87

Validating Connections

retained. This is beneficial to Java applications using connection pools, as the pool can use this feature tovalidate connections. Depending on your connection pool and configuration, this validation can be carriedout at different times:

1. Before the pool returns a connection to the application.

2. When the application returns a connection to the pool.

3. During periodic checks of idle connections.

To use this feature, specify a validation query in your connection pool that starts with /* ping*/. Note that the syntax must be exactly as specified. This will cause the driver send a ping to theserver and return a dummy lightweight result set. When using a ReplicationConnection orLoadBalancedConnection, the ping will be sent across all active connections.

It is critical that the syntax be specified correctly. The syntax needs to be exact for reasons of efficiency, asthis test is done for every statement that is executed:

protected static final String PING_MARKER = "/* ping */";...if (sql.charAt(0) == '/') {if (sql.startsWith(PING_MARKER)) {doPingInstead();...

None of the following snippets will work, because the ping syntax is sensitive to whitespace, capitalization,and placement:

sql = "/* PING */ SELECT 1";sql = "SELECT 1 /* ping*/";sql = "/*ping*/ SELECT 1";sql = " /* ping */ SELECT 1";sql = "/*to ping or not to ping*/ SELECT 1";

All of the previous statements will issue a normal SELECT statement and will not be transformed intothe lightweight ping. Further, for load-balanced connections, the statement will be executed against oneconnection in the internal pool, rather than validating each underlying physical connection. This resultsin the non-active physical connections assuming a stale state, and they may die. If Connector/J then re-balances, it might select a dead connection, resulting in an exception being passed to the application.To help prevent this, you can use loadBalanceValidateConnectionOnSwapServer to validate theconnection before use.

If your Connector/J deployment uses a connection pool that allows you to specify a validation query, takeadvantage of it, but ensure that the query starts exactly with /* ping */. This is particularly importantif you are using the load-balancing or replication-aware features of Connector/J, as it will help keep aliveconnections which otherwise will go stale and die, causing problems later.

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Chapter 8 Multi-Host Connections

Table of Contents8.1 Configuring Server Failover ......................................................................................................... 898.2 Configuring Load Balancing with Connector/J .............................................................................. 928.3 Configuring Source/Replica Replication with Connector/J .............................................................. 948.4 Advanced Load-balancing and Failover Configuration ................................................................... 98

The following sections discuss a number of topics that involve multi-host connections, namely, server load-balancing, failover, and replication.

Developers should know the following things about multi-host connections that are managed throughConnector/J:

• Each multi-host connection is a wrapper of the underlying physical connections.

• Each of the underlying physical connections has its own session. Sessions cannot be tracked, shared, orcopied, given the MySQL architecture.

• Every switch between physical connections means a switch between sessions.

• Within a transaction boundary, there are no switches between physical connections. Beyond atransaction boundary, there is no guarantee that a switch does not occur.

Note

If an application reuses session-scope data (for example, variables, SSPs)beyond a transaction boundary, failures are possible, as a switch between thephysical connections (which is also a switch between sessions) might occur.Therefore, the application should re-prepare the session data and also restart thelast transaction in case of an exception, or it should re-prepare session data foreach new transaction if it does not want to deal with exception handling.

8.1 Configuring Server Failover

MySQL Connector/J supports server failover. A failover happens when connection-related errors occur foran underlying, active connection. The connection errors are, by default, propagated to the client, whichhas to handle them by, for example, recreating the working objects (Statement, ResultSet, etc.) andrestarting the processes. Sometimes, the driver might eventually fall back to the original host automaticallybefore the client application continues to run, in which case the host switch is transparent and the clientapplication will not even notice it.

A connection using failover support works just like a standard connection: the client does not experienceany disruptions in the failover process. This means the client can rely on the same connection instanceeven if two successive statements might be executed on two different physical hosts. However, this doesnot mean the client does not have to deal with the exception that triggered the server switch.

The failover is configured at the initial setup stage of the server connection by the connection URL (seeexplanations for its format here):

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Configuring Connection Access Mode

jdbc:mysql://[primary host][:port],[secondary host 1][:port][,[secondary host 2][:port]]...[/[database]]»[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

The host list in the connection URL comprises of two types of hosts, the primary and the secondary. Whenstarting a new connection, the driver always tries to connect to the primary host first and, if required, failsover to the secondary hosts on the list sequentially when communication problems are experienced. Evenif the initial connection to the primary host fails and the driver gets connected to a secondary host, theprimary host never loses its special status: for example, it can be configured with an access mode distinctfrom those of the secondary hosts, and it can be put on a higher priority when a host is to be picked duringa failover process.

The failover support is configured by the following connection properties (their functions are explained inthe paragraphs below):

• failOverReadOnly

• secondsBeforeRetryMaster

• queriesBeforeRetryMaster

• retriesAllDown

• autoReconnect

• autoReconnectForPools

Configuring Connection Access Mode

As with any standard connection, the initial connection to the primary host is in read/write mode. However,if the driver fails to establish the initial connection to the primary host and it automatically switches to thenext host on the list, the access mode now depends on the value of the property failOverReadOnly,which is “true” by default. The same happens if the driver is initially connected to the primary host and,because of some connection failure, it fails over to a secondary host. Every time the connection fallsback to the primary host, its access mode will be read/write, irrespective of whether or not the primaryhost has been connected to before. The connection access mode can be changed any time at runtimeby calling the method Connection.setReadOnly(boolean), which partially overrides the propertyfailOverReadOnly. When failOverReadOnly=false and the access mode is explicitly set to eithertrue or false, it becomes the mode for every connection after a host switch, no matter what host typeare we connected to; but, if failOverReadOnly=true, changing the access mode to read/write isonly possible if the driver is connecting to the primary host; however, even if the access mode cannot bechanged for the current connection, the driver remembers the client's last intention and, when falling backto the primary host, that is the mode that will be used. For an illustration, see the following successions ofevents with a two-host connection.

• Sequence A, with failOverReadOnly=true:

1. Connects to primary host in read/write mode

2. Sets Connection.setReadOnly(true); primary host now in read-only mode

3. Failover event; connects to secondary host in read-only mode

4. Sets Connection.setReadOnly(false); secondary host remains in read-only mode

5. Falls back to primary host; connection now in read/write mode

• Sequence B, with failOverReadOnly=false

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Configuring Fallback to Primary Host

1. Connects to primary host in read/write mode

2. Sets Connection.setReadOnly(true); primary host now in read-only mode

3. Failover event; connects to secondary host in read-only mode

4. Set Connection.setReadOnly(false); connection to secondary host switches to read/writemode

5. Falls back to primary host; connection now in read/write mode

The difference between the two scenarios is in step 4: the access mode for the secondary host insequence A does not change at that step, but the driver remembers and uses the set mode when fallingback to the primary host, which would be read-only otherwise; but in sequence B, the access mode for thesecondary host changes immediately.

Configuring Fallback to Primary Host

As already mentioned, the primary host is special in the failover arrangement when it comes to thehost's access mode. Additionally, the driver tries to fall back to the primary host as soon as possible bydefault, even if no communication exception occurs. Two properties, secondsBeforeRetryMaster andqueriesBeforeRetryMaster, determine when the driver is ready to retry a reconnection to the primaryhost (the Master in the property names stands for the primary host of our connection URL, which is notnecessarily a source host in a replication setup; the naming was maintained for back compatibility withConnector/J versions prior to 5.1.35):

• secondsBeforeRetryMaster determines how much time the driver waits before trying to fall back tothe primary host

• queriesBeforeRetryMaster determines the number of queries that are executedbefore the driver tries to fall back to the primary host. Note that for the driver, each call to aStatement.execute*() method increments the query execution counter; therefore, when calls aremade to Statement.executeBatch() or if allowMultiQueries or rewriteBatchStatementsare enabled, the driver may not have an accurate count of the actual number of queries executed on theserver. Also, the driver calls the Statement.execute*() methods internally in several occasions. Allthese mean you can only use queriesBeforeRetryMaster only as a coarse specification for when tofall back to the primary host.

In general, an attempt to fallback to the primary host is made when at least one of the conditions specifiedby the two properties is met, and the attempt always takes place at transaction boundaries. However,if auto-commit is turned off, the check happens only when the method Connection.commit() orConnection.rollback() is called. The automatic fallback to the primary host can be turned off bysetting simultaneously secondsBeforeRetryMaster and queriesBeforeRetryMaster to “0”.Setting only one of the properties to “0” only disables one part of the check.

Configuring Reconnection Attempts

When establishing a new connection or when a failover event occurs, the driver tries to connectsuccessively to the next candidate on the host list. When the end of the list has been reached, it restartsall over again from the beginning of the list; however, the primary host is skipped over, if (a) NOT allthe secondary hosts have already been tested at least once, AND (b) the fallback conditions defined bysecondsBeforeRetryMaster and queriesBeforeRetryMaster are not yet fulfilled. Each run-through of the whole host list, (which is not necessarily completed at the end of the host list) counts as asingle connection attempt. The driver tries as many connection attempts as specified by the value of theproperty retriesAllDown.

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Seamless Reconnection

Seamless Reconnection

Although not recommended, you can make the driver perform failovers without invalidating theactive Statement or ResultSet instances by setting either the parameter autoReconnect orautoReconnectForPools to true. This allows the client to continue using the same object instancesafter a failover event, without taking any exceptional measures. This, however, may lead to unexpectedresults: for example, if the driver is connected to the primary host with read/write access mode and it fails-over to a secondary host in real-only mode, further attempts to issue data-changing queries will resultin errors, and the client will not be aware of that. This limitation is particularly relevant when using datastreaming: after the failover, the ResultSet looks to be alright, but the underlying connection may havechanged already, and no backing cursor is available anymore.

8.2 Configuring Load Balancing with Connector/J

Connector/J has long provided an effective means to distribute read/write load across multiple MySQLserver instances for Cluster or source-source replication deployments. Starting with Connector/J 5.1.3, youcan now dynamically configure load-balanced connections, with no service outage. In-process transactionsare not lost, and no application exceptions are generated if any application is trying to use that particularserver instance.

The load balancing is configured at the initial setup stage of the server connection by the followingconnection URL, which has a similar format as the general URL for MySQL connection, but a specializedscheme:

jdbc:mysql:loadbalance://[host1][:port],[host2][:port][,[host3][:port]]...[/[database]] »[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

There are two configuration properties associated with this functionality:

• loadBalanceConnectionGroup – This provides the ability to group connections from differentsources. This allows you to manage these JDBC sources within a single class loader in any combinationyou choose. If they use the same configuration, and you want to manage them as a logical singlegroup, give them the same name. This is the key property for management: if you do not define aname (string) for loadBalanceConnectionGroup, you cannot manage the connections. All load-balanced connections sharing the same loadBalanceConnectionGroup value, regardless of how theapplication creates them, will be managed together.

• loadBalanceEnableJMX – The ability to manage the connections is exposed when you definea loadBalanceConnectionGroup; but if you want to manage this externally, enable JMX bysetting this property to true. This enables a JMX implementation, which exposes the managementand monitoring operations of a connection group. Further, start your application with the -Dcom.sun.management.jmxremote JVM flag. You can then perform connect and perform operationsusing a JMX client such as jconsole.

Once a connection has been made using the correct connection properties, a number of monitoringproperties are available:

• Current active host count.

• Current active physical connection count.

• Current active logical connection count.

• Total logical connections created.

• Total transaction count.

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The following management operations can also be performed:

• Add host.

• Remove host.

The JMX interface, com.mysql.jdbc.jmx.LoadBalanceConnectionGroupManagerMBean, has thefollowing methods:

• int getActiveHostCount(String group);

• int getTotalHostCount(String group);

• long getTotalLogicalConnectionCount(String group);

• long getActiveLogicalConnectionCount(String group);

• long getActivePhysicalConnectionCount(String group);

• long getTotalPhysicalConnectionCount(String group);

• long getTotalTransactionCount(String group);

• void removeHost(String group, String host) throws SQLException;

• void stopNewConnectionsToHost(String group, String host) throws SQLException;

• void addHost(String group, String host, boolean forExisting);

• String getActiveHostsList(String group);

• String getRegisteredConnectionGroups();

The getRegisteredConnectionGroups() method returns the names of all connection groups definedin that class loader.

You can test this setup with the following code:

public class Test {

private static String URL = "jdbc:mysql:loadbalance://" + "localhost:3306,localhost:3310/test?" + "loadBalanceConnectionGroup=first&loadBalanceEnableJMX=true";

public static void main(String[] args) throws Exception { new Thread(new Repeater()).start(); new Thread(new Repeater()).start(); new Thread(new Repeater()).start(); }

static Connection getNewConnection() throws SQLException, ClassNotFoundException { Class.forName("com.mysql.jdbc.Driver"); return DriverManager.getConnection(URL, "root", ""); }

static void executeSimpleTransaction(Connection c, int conn, int trans){ try { c.setAutoCommit(false); Statement s = c.createStatement(); s.executeQuery("SELECT SLEEP(1) /* Connection: " + conn + ", transaction: " + trans + " */"); c.commit();

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Configuring Source/Replica Replication with Connector/J

} catch (SQLException e) { e.printStackTrace(); } }

public static class Repeater implements Runnable { public void run() { for(int i=0; i < 100; i++){ try { Connection c = getNewConnection(); for(int j=0; j < 10; j++){ executeSimpleTransaction(c, i, j); Thread.sleep(Math.round(100 * Math.random())); } c.close(); Thread.sleep(100); } catch (Exception e) { e.printStackTrace(); } } } }}

After compiling, the application can be started with the -Dcom.sun.management.jmxremoteflag, to enable remote management. jconsole can then be started. The Test main classwill be listed by jconsole. Select this and click Connect. You can then navigate to thecom.mysql.jdbc.jmx.LoadBalanceConnectionGroupManager bean. At this point, you can click onvarious operations and examine the returned result.

If you now had an additional instance of MySQL running on port 3309, you could ensure that Connector/Jstarts using it by using the addHost(), which is exposed in jconsole. Note that these operations can beperformed dynamically without having to stop the application running.

For further information on the combination of load balancing and failover, see Section 8.4, “AdvancedLoad-balancing and Failover Configuration”.

8.3 Configuring Source/Replica Replication with Connector/J

This section describe a number of features of Connector/J's support for replication-aware deployments.

The replication is configured at the initial setup stage of the server connection by the connection URL,which has a similar format as the general URL for MySQL connection, but a specialized scheme:

jdbc:mysql:replication://[source host][:port],[replica host 1][:port][,[replica host 2][:port]]...[/[database]] »[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

Users may specify the property allowMasterDownConnections=true to allow Connection objectsto be created even though no source hosts are reachable. Such Connection objects report they areread-only, and isMasterConnection() returns false for them. The Connection tests for availablesource hosts when Connection.setReadOnly(false) is called, throwing an SQLException if it cannotestablish a connection to a source, or switching to a source connection if the host is available.

For Connector/J 5.1.38 and later, users may specify the propertyallowSlavesDownConnections=true to allow Connection objects to be created even thoughno replica hosts are reachable. A Connection then, at runtime, tests for available replica hostswhen Connection.setReadOnly(true) is called (see explanation for the method below),throwing an SQLException if it cannot establish a connection to a replica, unless the propertyreadFromMasterWhenNoSlaves is set to be “true” (see below for a description of the property).

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Scaling out Read Load by Distributing Read Traffic to Replicas

Scaling out Read Load by Distributing Read Traffic to Replicas

Connector/J 3.1.7 and higher includes a variant of the driver that will automatically send queries toa read/write source, or a failover or round-robin loadbalanced set of replicas based on the state ofConnection.getReadOnly().

An application signals that it wants a transaction to be read-only by callingConnection.setReadOnly(true). The replication-aware connection will use one of the replicaconnections, which are load-balanced per replica host using a round-robin scheme. A givenconnection is sticky to a replica until a transaction boundary command (a commit or rollback) isissued, or until the replica is removed from service. For Connector/J 5.1.38 and later, after callingConnection.setReadOnly(true), if you want to allow connection to a source when no replicasare available, set the property readFromMasterWhenNoSlaves to “true.” Notice that the sourcehost will be used in read-only state in those cases, as if it is a replica host. Also notice that settingreadFromMasterWhenNoSlaves=true might result in an extra load for the source host in a transparentmanner.

If you have a write transaction, or if you have a read that is time-sensitive (remember, replication in MySQLis asynchronous), set the connection to be not read-only, by calling Connection.setReadOnly(false)and the driver will ensure that further calls are sent to the source MySQL server. The driver takes care ofpropagating the current state of autocommit, isolation level, and catalog between all of the connections thatit uses to accomplish this load balancing functionality.

To enable this functionality, use the com.mysql.jdbc.ReplicationDriver class when configuringyour application server's connection pool or when creating an instance of a JDBC driver for yourstandalone application. Because it accepts the same URL format as the standard MySQL JDBC driver,ReplicationDriver does not currently work with java.sql.DriverManager-based connectioncreation unless it is the only MySQL JDBC driver registered with the DriverManager .

Here is a short example of how ReplicationDriver might be used in a standalone application:

import java.sql.Connection;import java.sql.ResultSet;import java.util.Properties;

import com.mysql.jdbc.ReplicationDriver;

public class ReplicationDriverDemo {

public static void main(String[] args) throws Exception { ReplicationDriver driver = new ReplicationDriver();

Properties props = new Properties();

// We want this for failover on the replicas props.put("autoReconnect", "true");

// We want to load balance between the replicas props.put("roundRobinLoadBalance", "true");

props.put("user", "foo"); props.put("password", "password");

// // Looks like a normal MySQL JDBC url, with a // comma-separated list of hosts, the first // being the 'source', the rest being any number // of replicas that the driver will load balance against //

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Connection conn = driver.connect("jdbc:mysql:replication://source,replica1,replica2,replica3/test", props);

// // Perform read/write work on the source // by setting the read-only flag to "false" //

conn.setReadOnly(false); conn.setAutoCommit(false); conn.createStatement().executeUpdate("UPDATE some_table ...."); conn.commit();

// // Now, do a query from a replica, the driver automatically picks one // from the list //

conn.setReadOnly(true);

ResultSet rs = conn.createStatement().executeQuery("SELECT a,b FROM alt_table");

....... }}

Consider using the Load Balancing JDBC Pool (lbpool) tool, which provides a wrapper around thestandard JDBC driver and enables you to use DB connection pools that includes checks for system failuresand uneven load distribution. For more information, see Load Balancing JDBC Driver for MySQL (mysql-lbpool).

Support for Multiple-Source Replication Topographies

Since Connector/J 5.1.27, multi-source replication topographies are supported.

The connection URL for replication discussed earlier (i.e., in the format ofjdbc:mysql:replication://source,replica1,replica2,replica3/test) assumes that thefirst (and only the first) host is the source. Supporting deployments with an arbitrary number of sourcesand replicas requires the URL syntax for specifying the hosts and the properties for specific hosts (which isdiscussed here) and the use of the property type=[master|slave]; for example:

jdbc:mysql:replication://address=(type=master)(host=source1host),address=(type=master)(host=source2host),address=(type=slave)(host=replica1host)/database

Connector/J uses a load-balanced connection internally for management of the source connections, whichmeans that ReplicationConnection, when configured to use multiple sources, exposes the sameoptions to balance load across source hosts as described in Section 8.2, “Configuring Load Balancing withConnector/J”.

Live Reconfiguration of Replication Topography

Since Connector/J 5.1.28, live management of replication host (single or multi-source) topographies is alsosupported. This enables users to promote replicas for Java applications without requiring an applicationrestart.

The replication hosts are most effectively managed in the context of a replication connection group. AReplicationConnectionGroup class represents a logical grouping of connections which can be managedtogether. There may be one or more such replication connection groups in a given Java class loader (there

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http://code.google.com/p/mysql-lbpool/

http://code.google.com/p/mysql-lbpool/

ReplicationConnectionGroupManager

can be an application with two different JDBC resources needing to be managed independently). This keyclass exposes host management methods for replication connections, and ReplicationConnectionobjects register themselves with the appropriate ReplicationConnectionGroup if a value for the newreplicationConnectionGroup property is specified. The ReplicationConnectionGroup objecttracks these connections until they are closed, and it is used to manipulate the hosts associated with theseconnections.

Some important methods related to host management include:

• getMasterHosts(): Returns a collection of strings representing the hosts configured as sources

• getSlaveHosts(): Returns a collection of strings representing the hosts configured as replicas

• addSlaveHost(String host): Adds new host to pool of possible replica hosts for selection at startof new read-only workload

• promoteSlaveToMaster(String host): Removes the host from the pool of potential replicas forfuture read-only processes (existing read-only process is allowed to continue to completion) and addsthe host to the pool of potential source hosts

• removeSlaveHost(String host, boolean closeGently): Removes the host (host name matchmust be exact) from the list of configured replicas; if closeGently is false, existing connections whichhave this host as currently active will be closed hardly (application should expect exceptions)

• removeMasterHost(String host, boolean closeGently): Same as removeSlaveHost(),but removes the host from the list of configured sources

Some useful management metrics include:

• getConnectionCountWithHostAsSlave(String host): Returns the number ofReplicationConnection objects that have the given host configured as a possible replica

• getConnectionCountWithHostAsMaster(String host): Returns the number ofReplicationConnection objects that have the given host configured as a possible source

• getNumberOfSlavesAdded(): Returns the number of times a replica host has been dynamicallyadded to the group pool

• getNumberOfSlavesRemoved(): Returns the number of times a replica host has been dynamicallyremoved from the group pool

• getNumberOfSlavePromotions(): Returns the number of times a replica host has been promoted toa source

• getTotalConnectionCount(): Returns the number of ReplicationConnection objects which havebeen registered with this group

• getActiveConnectionCount(): Returns the number of ReplicationConnection objects currentlybeing managed by this group

ReplicationConnectionGroupManager

com.mysql.jdbc.ReplicationConnectionGroupManager provides access to the replicationconnection groups, together with some utility methods.

• getConnectionGroup(String groupName): Returns the ReplicationConnectionGroup objectmatching the groupName provided

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Using JMX for Managing Replication Hosts

The other methods in ReplicationConnectionGroupManager mirror those ofReplicationConnectionGroup, except that the first argument is a String group name. These methodswill operate on all matching ReplicationConnectionGroups, which are helpful for removing a server fromservice and have it decommissioned across all possible ReplicationConnectionGroups.

These methods might be useful for in-JVM management of replication hosts if an application triggerstopography changes. For managing host configurations from outside the JVM, JMX can be used.

Using JMX for Managing Replication Hosts

When Connector/J is started with replicationEnableJMX=true and a value setfor the property replicationConnectionGroup, a JMX MBean will be registered,allowing manipulation of replication hosts by a JMX client. The MBean interface is definedin com.mysql.jdbc.jmx.ReplicationGroupManagerMBean, and leverages theReplicationConnectionGroupManager static methods:

public abstract void addSlaveHost(String groupFilter, String host) throws SQLException; public abstract void removeSlaveHost(String groupFilter, String host) throws SQLException; public abstract void promoteSlaveToMaster(String groupFilter, String host) throws SQLException; public abstract void removeMasterHost(String groupFilter, String host) throws SQLException; public abstract String getMasterHostsList(String group); public abstract String getSlaveHostsList(String group); public abstract String getRegisteredConnectionGroups(); public abstract int getActiveMasterHostCount(String group); public abstract int getActiveSlaveHostCount(String group); public abstract int getSlavePromotionCount(String group); public abstract long getTotalLogicalConnectionCount(String group); public abstract long getActiveLogicalConnectionCount(String group);

8.4 Advanced Load-balancing and Failover Configuration

Connector/J provides a useful load-balancing implementation for MySQL Cluster or multi-sourcedeployments, as explained in Section 8.2, “Configuring Load Balancing with Connector/J” and Support forMultiple-Source Replication Topographies. As of Connector/J 5.1.12, this same implementation is used forbalancing load between read-only replicas with ReplicationDriver.

When trying to balance workload between multiple servers, the driver has to determine when it is safe toswap servers, doing so in the middle of a transaction, for example, could cause problems. It is importantnot to lose state information. For this reason, Connector/J will only try to pick a new server when one of thefollowing happens:

1. At transaction boundaries (transactions are explicitly committed or rolled back).

2. A communication exception (SQL State starting with "08") is encountered.

3. When a SQLException matches conditions defined by user, using the extension points defined bythe loadBalanceSQLStateFailover, loadBalanceSQLExceptionSubclassFailover orloadBalanceExceptionChecker properties.

The third condition revolves around three new properties introduced with Connector/J 5.1.13. It allows youto control which SQLExceptions trigger failover.

• loadBalanceExceptionChecker - The loadBalanceExceptionChecker propertyis really the key. This takes a fully-qualified class name which implements the newcom.mysql.jdbc.LoadBalanceExceptionChecker interface. This interface is very simple, and youonly need to implement the following method:

public boolean shouldExceptionTriggerFailover(SQLException ex)

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A SQLException is passed in, and a boolean returned. A value of true triggers a failover, false doesnot.

You can use this to implement your own custom logic. An example where this might be useful is whendealing with transient errors when using MySQL Cluster, where certain buffers may become overloaded.The following code snippet illustrates this:

public class NdbLoadBalanceExceptionChecker extends StandardLoadBalanceExceptionChecker {

public boolean shouldExceptionTriggerFailover(SQLException ex) { return super.shouldExceptionTriggerFailover(ex) || checkNdbException(ex); }

private boolean checkNdbException(SQLException ex){ // Have to parse the message since most NDB errors // are mapped to the same DEMC. return (ex.getMessage().startsWith("Lock wait timeout exceeded") || (ex.getMessage().startsWith("Got temporary error") && ex.getMessage().endsWith("from NDB"))); }}

The code above extends com.mysql.jdbc.StandardLoadBalanceExceptionChecker,which is the default implementation. There are a few convenient shortcuts built into this, for thosewho want to have some level of control using properties, without writing Java code. This defaultimplementation uses the two remaining properties: loadBalanceSQLStateFailover andloadBalanceSQLExceptionSubclassFailover.

• loadBalanceSQLStateFailover - allows you to define a comma-delimited list of SQLState codeprefixes, against which a SQLException is compared. If the prefix matches, failover is triggered. So, forexample, the following would trigger a failover if a given SQLException starts with "00", or is "12345":

loadBalanceSQLStateFailover=00,12345

• loadBalanceSQLExceptionSubclassFailover - can be used in conjunction withloadBalanceSQLStateFailover or on its own. If you want certain subclasses of SQLException totrigger failover, simply provide a comma-delimited list of fully-qualified class or interface names to checkagainst. For example, if you want all SQLTransientConnectionExceptions to trigger failover, youwould specify:

loadBalanceSQLExceptionSubclassFailover=java.sql.SQLTransientConnectionException

While the three failover conditions enumerated earlier suit most situations, if autocommit is enabled,Connector/J never re-balances, and continues using the same physical connection. This can beproblematic, particularly when load-balancing is being used to distribute read-only load across multiplereplicas. However, Connector/J can be configured to re-balance after a certain number of statements areexecuted, when autocommit is enabled. This functionality is dependent upon the following properties:

• loadBalanceAutoCommitStatementThreshold – defines the number of matching statementswhich will trigger the driver to potentially swap physical server connections. The default value, 0, retainsthe behavior that connections with autocommit enabled are never balanced.

• loadBalanceAutoCommitStatementRegex – the regular expression against which statements mustmatch. The default value, blank, matches all statements. So, for example, using the following propertieswill cause Connector/J to re-balance after every third statement that contains the string “test”:

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Advanced Load-balancing and Failover Configuration

loadBalanceAutoCommitStatementThreshold=3loadBalanceAutoCommitStatementRegex=.*test.*

loadBalanceAutoCommitStatementRegex can prove useful in a number of situations. Yourapplication may use temporary tables, server-side session state variables, or connection state, whereletting the driver arbitrarily swap physical connections before processing is complete could cause dataloss or other problems. This allows you to identify a trigger statement that is only executed when it issafe to swap physical connections.

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Chapter 9 Using the Connector/J Interceptor ClassesAn interceptor is a software design pattern that provides a transparent way to extend or modify someaspect of a program, similar to a user exit. No recompiling is required. With Connector/J, the interceptorsare enabled and disabled by updating the connection string to refer to different sets of interceptor classesthat you instantiate.

The connection properties that control the interceptors are explained in Section 5.3, “ConfigurationProperties for Connector/J”:

• connectionLifecycleInterceptors, where you specify the fully qualified names of classes thatimplement the com.mysql.jdbc.ConnectionLifecycleInterceptor interface. In these kinds ofinterceptor classes, you might log events such as rollbacks, measure the time between transaction startand end, or count events such as calls to setAutoCommit().

• exceptionInterceptors, where you specify the fully qualified names of classes that implement thecom.mysql.jdbc.ExceptionInterceptor interface. In these kinds of interceptor classes, youmight add extra diagnostic information to exceptions that can have multiple causes or indicate a problemwith server settings. Because exceptionInterceptors classes are only called when handling aSQLException thrown from Connector/J code, they can be used even in production deploymentswithout substantial performance overhead.

• statementInterceptors, where you specify the fully qualified names of classes that implement thecom.mysql.jdbc.StatementInterceptorV2 interface. In these kinds of interceptor classes, youmight change or augment the processing done by certain kinds of statements, such as automaticallychecking for queried data in a memcached server, rewriting slow queries, logging information aboutstatement execution, or route requests to remote servers.

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Chapter 10 Using Logging Frameworks with SLF4JBesides its default logger com.mysql.cj.log.StandardLogger, which logs to stderr, Connector/J supports the SLF4J logging facade, allowing end users of applications using Connector/J to plugin logging frameworks of their own choices at deployment time. Popular logging frameworks such asjava.util.logging, logback, and log4j are supported by SLF4J. Follow these requirements to usea logging framework with SLF4J and Connector/J:

• In the development environment:

• Install on your system slf4j-api-x.y.z.jar (available at https://www.slf4j.org/download.html) andadd it to the Java classpath.

• In the code of your application, obtain an SLF4JLogger as a Log instantiated within aMysqlConnection, and then use the Log instance for your logging.

• On the deployment system:

• Install on your system slf4j-api-x.y.z.jar and add it to the Java classpath

• Install on your system the SLF4J binding for the logging framework of your choice and add itto your Java classpath. SLF4J bindings are available at, for example, https://www.slf4j.org/manual.html#swapping.

Note

Do not put more than one SLF4J binding in you Java classpath. Switch fromone logging framework to another by removing a binding and adding a new oneto the classpath.

• Install the logging framework of your choice on your system and add it to the Java classpath.

• Configure the logging framework of your choice. This often consists of setting up appenders orhandlers for log messages using a configuration file; see your logging framework's documentation fordetails.

• When connecting the application to the MySQL Server, set the Connector/J connection propertylogger to Slf4JLogger.

The log category name used by Connector/J with SLF4J is MySQL. See the SLF4J user manual for moredetails about using SLF4J, including discussions on Maven dependency and bindings. Here is a samplecode for using SLF4J with Connector/J:

import java.sql.DriverManager;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import com.mysql.jdbc.MySQLConnection;import com.mysql.jdbc.log.Log;

public class JDBCDemo { public static void main(String[] args) { Connection conn = null; Statement statement = null; ResultSet resultSet = null; Log logger = null;

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try { // Database parameters String url = "jdbc:mysql://myexample.com:3306/pets?logger=Slf4JLogger&explainSlowQueries=true"; String user = "user"; String password = "password"; // create a connection to the database conn = DriverManager.getConnection(url, user, password); logger = ((MySQLConnection)conn).getLog(); } catch (SQLException e) { System.err.println(e.getMessage()); System.exit(1); }

try { statement = conn.createStatement(); resultSet = statement.executeQuery("SELECT * FROM pets.dogs"); while(resultSet.next()){ System.out.printf("%d\t%s\t%s\t %4$ty.%4$tm.%4$td \n", resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3), resultSet.getDate(4)); } } catch(SQLException e) { logger.logWarn("Warning: Select failed!"); }

}

}

If you want to use, for example, Log4j 1.2.17 as your logging framework when running this program, useits binding to SLF4J: put slf4j-api-1.7.28.jar (SLF4J API module), slf4j-log4j12-1.7.28.jar(SLF4J's binding for Log4J 1.2), and log4j-1.2.17.jar (Log4J library) in your Java classpath.

Here is output of the program when the SELECT statement failed:

[2019-09-05 12:06:19,624] WARN 0[main] - WARN MySQL - Warning: Select failed!

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Chapter 11 Using Connector/J with TomcatThe following instructions are based on the instructions for Tomcat-5.x, available at http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html which is current at the time thisdocument was written.

First, install the .jar file that comes with Connector/J in $CATALINA_HOME/common/lib so that it isavailable to all applications installed in the container.

Next, configure the JNDI DataSource by adding a declaration resource to $CATALINA_HOME/conf/server.xml in the context that defines your web application:

<Context ....>

...

<Resource name="jdbc/MySQLDB" auth="Container" type="javax.sql.DataSource"/>

<ResourceParams name="jdbc/MySQLDB"> <parameter> <name>factory</name> <value>org.apache.commons.dbcp.BasicDataSourceFactory</value> </parameter>

<parameter> <name>maxActive</name> <value>10</value> </parameter>

<parameter> <name>maxIdle</name> <value>5</value> </parameter>

<parameter> <name>validationQuery</name> <value>SELECT 1</value> </parameter>

<parameter> <name>testOnBorrow</name> <value>true</value> </parameter>

<parameter> <name>testWhileIdle</name> <value>true</value> </parameter>

<parameter> <name>timeBetweenEvictionRunsMillis</name> <value>10000</value> </parameter>

<parameter> <name>minEvictableIdleTimeMillis</name> <value>60000</value> </parameter>

<parameter> <name>username</name> <value>someuser</value>

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</parameter>

<parameter> <name>password</name> <value>somepass</value> </parameter>

<parameter> <name>driverClassName</name> <value>com.mysql.jdbc.Driver</value> </parameter>

<parameter> <name>url</name> <value>jdbc:mysql://localhost:3306/test</value> </parameter>

</ResourceParams></Context>

Note that Connector/J 5.1.3 introduced a facility whereby, rather than use a validationQuery value ofSELECT 1, it is possible to use validationQuery with a value set to /* ping */. This sends a ping tothe server which then returns a fake result set. This is a lighter weight solution. It also has the advantagethat if using ReplicationConnection or LoadBalancedConnection type connections, the ping willbe sent across all active connections. The following XML snippet illustrates how to select this option:

<parameter> <name>validationQuery</name> <value>/* ping */</value></parameter>

Note that /* ping */ has to be specified exactly.

In general, follow the installation instructions that come with your version of Tomcat, as the way youconfigure datasources in Tomcat changes from time to time, and if you use the wrong syntax in your XMLfile, you will most likely end up with an exception similar to the following:

Error: java.sql.SQLException: Cannot load JDBC driver class 'null ' SQLstate: null

Note that the auto-loading of drivers having the META-INF/service/java.sql.Driver class inJDBC 4.0 and above causes an improper undeployment of the Connector/J driver in Tomcat on Windows.Namely, the Connector/J jar remains locked. This is an initialization problem that is not related to the driver.The possible workarounds, if viable, are as follows: use "antiResourceLocking=true" as a TomcatContext attribute, or remove the META-INF/ directory.

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JBoss AS is no longer maintained by its owner. Oracle does not provide support forJBoss AS. The Connector/J integration for JBoss is provided "as-is" and may stopfunctioning or be removed at anytime without notice.

These instructions cover JBoss-4.x. To make the JDBC driver classes available to the application server,put the JBoss common JDBC wrapper JAR archive (available from, for example, the Maven CentralRepository at http://central.maven.org/maven2/jboss/jboss-common-jdbc-wrapper/) into the lib directoryfor your server configuration (which is usually called default). Then, in the same configuration directory,in the subdirectory named deploy, create a datasource configuration file that ends with -ds.xml, whichtells JBoss to deploy this file as a JDBC Datasource. The file should have the following contents:

<datasources> <local-tx-datasource>

<jndi-name>MySQLDB</jndi-name> <connection-url>jdbc:mysql://localhost:3306/dbname</connection-url> <driver-class>com.mysql.jdbc.Driver</driver-class> <user-name>user</user-name> <password>pass</password>

<min-pool-size>5</min-pool-size>

<max-pool-size>20</max-pool-size>

<idle-timeout-minutes>5</idle-timeout-minutes>

<exception-sorter-class-name> com.mysql.jdbc.integration.jboss.ExtendedMysqlExceptionSorter </exception-sorter-class-name> <valid-connection-checker-class-name> com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker </valid-connection-checker-class-name>

</local-tx-datasource></datasources>

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Chapter 13 Using Connector/J with Spring

Table of Contents13.1 Using JdbcTemplate ............................................................................................................ 11013.2 Transactional JDBC Access .................................................................................................... 11113.3 Connection Pooling with Spring ............................................................................................... 113

The Spring Framework is a Java-based application framework designed for assisting in application designby providing a way to configure components. The technique used by Spring is a well known design patterncalled Dependency Injection (see Inversion of Control Containers and the Dependency Injection pattern).This article will focus on Java-oriented access to MySQL databases with Spring 2.0. For those wondering,there is a .NET port of Spring appropriately named Spring.NET.

Spring is not only a system for configuring components, but also includes support for aspect orientedprogramming (AOP). This is one of the main benefits and the foundation for Spring's resource andtransaction management. Spring also provides utilities for integrating resource management with JDBCand Hibernate.

For the examples in this section the MySQL world sample database will be used. The first task is to set upa MySQL data source through Spring. Components within Spring use the “bean” terminology. For example,to configure a connection to a MySQL server supporting the world sample database, you might use:

<util:map id="dbProps"> <entry key="db.driver" value="com.mysql.jdbc.Driver"/> <entry key="db.jdbcurl" value="jdbc:mysql://localhost/world"/> <entry key="db.username" value="myuser"/> <entry key="db.password" value="mypass"/></util:map>

In the above example, we are assigning values to properties that will be used in the configuration. For thedatasource configuration:

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${db.driver}"/> <property name="url" value="${db.jdbcurl}"/> <property name="username" value="${db.username}"/> <property name="password" value="${db.password}"/></bean>

The placeholders are used to provide values for properties of this bean. This means that you can specifyall the properties of the configuration in one place instead of entering the values for each property oneach bean. We do, however, need one more bean to pull this all together. The last bean is responsible foractually replacing the placeholders with the property values.

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="properties" ref="dbProps"/></bean>

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Now that we have our MySQL data source configured and ready to go, we write some Java code to accessit. The example below will retrieve three random cities and their corresponding country using the datasource we configured with Spring.

// Create a new application context. this processes the Spring configApplicationContext ctx = new ClassPathXmlApplicationContext("ex1appContext.xml");// Retrieve the data source from the application context DataSource ds = (DataSource) ctx.getBean("dataSource");// Open a database connection using Spring's DataSourceUtilsConnection c = DataSourceUtils.getConnection(ds);try { // retrieve a list of three random cities PreparedStatement ps = c.prepareStatement( "select City.Name as 'City', Country.Name as 'Country' " + "from City inner join Country on City.CountryCode = Country.Code " + "order by rand() limit 3"); ResultSet rs = ps.executeQuery(); while(rs.next()) { String city = rs.getString("City"); String country = rs.getString("Country"); System.out.printf("The city %s is in %s%n", city, country); }} catch (SQLException ex) { // something has failed and we print a stack trace to analyse the error ex.printStackTrace(); // ignore failure closing connection try { c.close(); } catch (SQLException e) { }} finally { // properly release our connection DataSourceUtils.releaseConnection(c, ds);}

This is very similar to normal JDBC access to MySQL with the main difference being that we are usingDataSourceUtils instead of the DriverManager to create the connection.

While it may seem like a small difference, the implications are somewhat far reaching. Spring managesthis resource in a way similar to a container managed data source in a J2EE application server. When aconnection is opened, it can be subsequently accessed in other parts of the code if it is synchronized witha transaction. This makes it possible to treat different parts of your application as transactional instead ofpassing around a database connection.

13.1 Using JdbcTemplateSpring makes extensive use of the Template method design pattern (see Template MethodPattern). Our immediate focus will be on the JdbcTemplate and related classes, specificallyNamedParameterJdbcTemplate. The template classes handle obtaining and releasing a connection fordata access when one is needed.

The next example shows how to use NamedParameterJdbcTemplate inside of a DAO (Data AccessObject) class to retrieve a random city given a country code.

public class Ex2JdbcDao { /** * Data source reference which will be provided by Spring. */ private DataSource dataSource;

/** * Our query to find a random city given a country code. Notice * the ":country" parameter toward the end. This is called a * named parameter. */

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private String queryString = "select Name from City " + "where CountryCode = :country order by rand() limit 1";

/** * Retrieve a random city using Spring JDBC access classes. */ public String getRandomCityByCountryCode(String cntryCode) { // A template that permits using queries with named parameters NamedParameterJdbcTemplate template = new NamedParameterJdbcTemplate(dataSource); // A java.util.Map is used to provide values for the parameters Map params = new HashMap(); params.put("country", cntryCode); // We query for an Object and specify what class we are expecting return (String)template.queryForObject(queryString, params, String.class); }

/** * A JavaBean setter-style method to allow Spring to inject the data source. * @param dataSource */ public void setDataSource(DataSource dataSource) { this.dataSource = dataSource; }}

The focus in the above code is on the getRandomCityByCountryCode() method. We pass a countrycode and use the NamedParameterJdbcTemplate to query for a city. The country code is placed in aMap with the key "country", which is the parameter is named in the SQL query.

To access this code, you need to configure it with Spring by providing a reference to the data source.

<bean id="dao" class="code.Ex2JdbcDao"> <property name="dataSource" ref="dataSource"/></bean>

At this point, we can just grab a reference to the DAO from Spring and callgetRandomCityByCountryCode().

// Create the application context ApplicationContext ctx = new ClassPathXmlApplicationContext("ex2appContext.xml"); // Obtain a reference to our DAO Ex2JdbcDao dao = (Ex2JdbcDao) ctx.getBean("dao");

String countryCode = "USA";

// Find a few random cities in the US for(int i = 0; i < 4; ++i) System.out.printf("A random city in %s is %s%n", countryCode, dao.getRandomCityByCountryCode(countryCode));

This example shows how to use Spring's JDBC classes to completely abstract away the use of traditionalJDBC classes including Connection and PreparedStatement.

13.2 Transactional JDBC Access

You might be wondering how we can add transactions into our code if we do not deal directly withthe JDBC classes. Spring provides a transaction management package that not only replaces JDBCtransaction management, but also enables declarative transaction management (configuration instead ofcode).

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Transactional JDBC Access

To use transactional database access, we will need to change the storage engine of the tables in the worlddatabase. The downloaded script explicitly creates MyISAM tables which do not support transactionalsemantics. The InnoDB storage engine does support transactions and this is what we will be using. Wecan change the storage engine with the following statements.

ALTER TABLE City ENGINE=InnoDB;ALTER TABLE Country ENGINE=InnoDB;ALTER TABLE CountryLanguage ENGINE=InnoDB;

A good programming practice emphasized by Spring is separating interfaces and implementations. Whatthis means is that we can create a Java interface and only use the operations on this interface without anyinternal knowledge of what the actual implementation is. We will let Spring manage the implementation andwith this it will manage the transactions for our implementation.

First you create a simple interface:

public interface Ex3Dao { Integer createCity(String name, String countryCode, String district, Integer population);}

This interface contains one method that will create a new city record in the database and return the id ofthe new record. Next you need to create an implementation of this interface.

public class Ex3DaoImpl implements Ex3Dao { protected DataSource dataSource; protected SqlUpdate updateQuery; protected SqlFunction idQuery;

public Integer createCity(String name, String countryCode, String district, Integer population) { updateQuery.update(new Object[] { name, countryCode, district, population }); return getLastId(); }

protected Integer getLastId() { return idQuery.run(); }}

You can see that we only operate on abstract query objects here and do not deal directly with the JDBCAPI. Also, this is the complete implementation. All of our transaction management will be dealt with in theconfiguration. To get the configuration started, we need to create the DAO.

<bean id="dao" class="code.Ex3DaoImpl"> <property name="dataSource" ref="dataSource"/> <property name="updateQuery">...</property> <property name="idQuery">...</property></bean>

Now you need to set up the transaction configuration. The first thing you must do is create transactionmanager to manage the data source and a specification of what transaction properties are required for thedao methods.

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/></bean>

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<tx:advice id="txAdvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="*"/> </tx:attributes></tx:advice>

The preceding code creates a transaction manager that handles transactions for the data source providedto it. The txAdvice uses this transaction manager and the attributes specify to create a transaction for allmethods. Finally you need to apply this advice with an AOP pointcut.

<aop:config> <aop:pointcut id="daoMethods" expression="execution(* code.Ex3Dao.*(..))"/> <aop:advisor advice-ref="txAdvice" pointcut-ref="daoMethods"/></aop:config>

This basically says that all methods called on the Ex3Dao interface will be wrapped in a transaction. Tomake use of this, you only have to retrieve the dao from the application context and call a method on thedao instance.

Ex3Dao dao = (Ex3Dao) ctx.getBean("dao");Integer id = dao.createCity(name, countryCode, district, pop);

We can verify from this that there is no transaction management happening in our Java code and it is allconfigured with Spring. This is a very powerful notion and regarded as one of the most beneficial featuresof Spring.

13.3 Connection Pooling with SpringIn many situations, such as web applications, there will be a large number of small database transactions.When this is the case, it usually makes sense to create a pool of database connections available for webrequests as needed. Although MySQL does not spawn an extra process when a connection is made,there is still a small amount of overhead to create and set up the connection. Pooling of connections alsoalleviates problems such as collecting large amounts of sockets in the TIME_WAIT state.

Setting up pooling of MySQL connections with Spring is as simple as changing the data sourceconfiguration in the application context. There are a number of configurations that we can use. Thefirst example is based on the Jakarta Commons DBCP library. The example below replaces the sourceconfiguration that was based on DriverManagerDataSource with DBCP's BasicDataSource.

<bean id="dataSource" destroy-method="close" class="org.apache.commons.dbcp.BasicDataSource"> <property name="driverClassName" value="${db.driver}"/> <property name="url" value="${db.jdbcurl}"/> <property name="username" value="${db.username}"/> <property name="password" value="${db.password}"/> <property name="initialSize" value="3"/></bean>

The configuration of the two solutions is very similar. The difference is that DBCP will pool connectionsto the database instead of creating a new connection every time one is requested. We have also set aparameter here called initialSize. This tells DBCP that we want three connections in the pool when itis created.

Another way to configure connection pooling is to configure a data source in our J2EE application server.Using JBoss as an example, you can set up the MySQL connection pool by creating a file called mysql-

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local-ds.xml and placing it in the server/default/deploy directory in JBoss. Once we have this setup, wecan use JNDI to look it up. With Spring, this lookup is very simple. The data source configuration looks likethis.

<jee:jndi-lookup id="dataSource" jndi-name="java:MySQL_DS"/>

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Chapter 14 Using Connector/J with GlassFish

Table of Contents14.1 A Simple JSP Application with GlassFish, Connector/J and MySQL ........................................... 11614.2 A Simple Servlet with GlassFish, Connector/J and MySQL ........................................................ 118

This section explains how to use MySQL Connector/J with GlassFish ™ Server Open Source Edition 3.0.1.GlassFish can be downloaded from the GlassFish website.

Once GlassFish is installed, make sure it can access MySQL Connector/J. To do this, copy the MySQLConnector/J jar file to the domain-dir/lib directory. For example, copy mysql-connector-java-5.1.30-bin.jar to C:\glassfish-install-path\domains\domain-name\lib. Restartthe GlassFish Application Server. For more information, see “Integrating the JDBC Driver” in GlassFishServer Open Source Edition Administration Guide, available at GlassFish Server Documentation.

You are now ready to create JDBC Connection Pools and JDBC Resources.

Creating a Connection Pool

1. In the GlassFish Administration Console, using the navigation tree navigate to Resources, JDBC,Connection Pools.

2. In the JDBC Connection Pools frame click New. You will enter a two step wizard.

3. In the Name field under General Settings enter the name for the connection pool, for example enterMySQLConnPool.

4. In the Resource Type field, select javax.sql.DataSource from the drop-down listbox.

5. In the Database Vendor field, select MySQL from the drop-down listbox. Click Next to go to the nextpage of the wizard.

6. You can accept the default settings for General Settings, Pool Settings and Transactions for thisexample. Scroll down to Additional Properties.

7. In Additional Properties you will need to ensure the following properties are set:

• ServerName - The server to connect to. For local testing this will be localhost.

• User - The user name with which to connect to MySQL.

• Password - The corresponding password for the user.

• DatabaseName - The database to connect to, for example the sample MySQL database World.

8. Click Finish to exit the wizard. You will be taken to the JDBC Connection Pools page where allcurrent connection pools, including the one you just created, will be displayed.

9. In the JDBC Connection Pools frame click on the connection pool you just created. Here, youcan review and edit information about the connection pool. Because Connector/J does not supportoptimized validation queries, go to the Advanced tab, and under Connection Validation, configure thefollowing settings:

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• Connection Validation - select Required.

• Validation Method - select table from the drop-down menu.

• Table Name - enter DUAL.

10. To test your connection pool click the Ping button at the top of the frame. A message will be displayedconfirming correct operation or otherwise. If an error message is received recheck the previous steps,and ensure that MySQL Connector/J has been correctly copied into the previously specified location.

Now that you have created a connection pool you will also need to create a JDBC Resource (data source)for use by your application.

Creating a JDBC Resource

Your Java application will usually reference a data source object to establish a connection with thedatabase. This needs to be created first using the following procedure.

• Using the navigation tree in the GlassFish Administration Console, navigate to Resources, JDBC,JDBC Resources. A list of resources will be displayed in the JDBC Resources frame.

• Click New. The New JDBC Resource frame will be displayed.

• In the JNDI Name field, enter the JNDI name that will be used to access this resource, for example enterjdbc/MySQLDataSource.

• In the Pool Name field, select a connection pool you want this resource to use from the drop-downlistbox.

• Optionally, you can enter a description into the Description field.

• Additional properties can be added if required.

• Click OK to create the new JDBC resource. The JDBC Resources frame will list all available JDBCResources.

14.1 A Simple JSP Application with GlassFish, Connector/J andMySQL

This section shows how to deploy a simple JSP application on GlassFish, that connects to a MySQLdatabase.

This example assumes you have already set up a suitable Connection Pool and JDBC Resource, asexplained in the preceding sections. It is also assumed you have a sample database installed, such asworld.

The main application code, index.jsp is presented here:

<%@ page import="java.sql.*, javax.sql.*, java.io.*, javax.naming.*" %><html><head><title>Hello world from JSP</title></head><body><% InitialContext ctx; DataSource ds; Connection conn; Statement stmt;

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ResultSet rs;

try { ctx = new InitialContext(); ds = (DataSource) ctx.lookup("java:comp/env/jdbc/MySQLDataSource"); //ds = (DataSource) ctx.lookup("jdbc/MySQLDataSource"); conn = ds.getConnection(); stmt = conn.createStatement(); rs = stmt.executeQuery("SELECT * FROM Country");

while(rs.next()) {%> <h3>Name: <%= rs.getString("Name") %></h3> <h3>Population: <%= rs.getString("Population") %></h3><% } } catch (SQLException se) {%> <%= se.getMessage() %><% } catch (NamingException ne) {%> <%= ne.getMessage() %><% }%></body></html>

In addition two XML files are required: web.xml, and sun-web.xml. There may be other files present,such as classes and images. These files are organized into the directory structure as follows:

index.jspWEB-INF | - web.xml - sun-web.xml

The code for web.xml is:

<?xml version="1.0" encoding="utf-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>HelloWebApp</display-name> <distributable/> <resource-ref> <res-ref-name>jdbc/MySQLDataSource</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> <res-sharing-scope>Shareable</res-sharing-scope> </resource-ref></web-app>

The code for sun-web.xml is:

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE sun-web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Application Server 8.1 Servlet 2.4//EN" "http://www.sun.com/software/appserver/dtds/sun-web-app_2_4-1.dtd"><sun-web-app> <context-root>HelloWebApp</context-root> <resource-ref> <res-ref-name>jdbc/MySQLDataSource</res-ref-name>

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<jndi-name>jdbc/MySQLDataSource</jndi-name> </resource-ref></sun-web-app>

These XML files illustrate a very important aspect of running JDBC applications on GlassFish. OnGlassFish it is important to map the string specified for a JDBC resource to its JNDI name, as set up in theGlassFish administration console. In this example, the JNDI name for the JDBC resource, as specified inthe GlassFish Administration console when creating the JDBC Resource, was jdbc/MySQLDataSource.This must be mapped to the name given in the application. In this example the name specified in theapplication, jdbc/MySQLDataSource, and the JNDI name, happen to be the same, but this does notnecessarily have to be the case. Note that the XML element <res-ref-name> is used to specify the name asused in the application source code, and this is mapped to the JNDI name specified using the <jndi-name>element, in the file sun-web.xml. The resource also has to be created in the web.xml file, although themapping of the resource to a JNDI name takes place in the sun-web.xml file.

If you do not have this mapping set up correctly in the XML files you will not be able to lookup the datasource using a JNDI lookup string such as:

ds = (DataSource) ctx.lookup("java:comp/env/jdbc/MySQLDataSource");

You will still be able to access the data source directly using:

ds = (DataSource) ctx.lookup("jdbc/MySQLDataSource");

With the source files in place, in the correct directory structure, you are ready to deploy the application:

1. In the navigation tree, navigate to Applications - the Applications frame will be displayed. ClickDeploy.

2. You can now deploy an application packaged into a single WAR file from a remote client, or you canchoose a packaged file or directory that is locally accessible to the server. If you are simply testing anapplication locally you can simply point GlassFish at the directory that contains your application, withoutneeding to package the application into a WAR file.

3. Now select the application type from the Type drop-down listbox, which in this example is Webapplication.

4. Click OK.

Now, when you navigate to the Applications frame, you will have the option to Launch, Redeploy, orRestart your application. You can test your application by clicking Launch. The application will connectionto the MySQL database and display the Name and Population of countries in the Country table.

14.2 A Simple Servlet with GlassFish, Connector/J and MySQL

This section describes a simple servlet that can be used in the GlassFish environment to access a MySQLdatabase. As with the previous section, this example assumes the sample database world is installed.

The project is set up with the following directory structure:

index.htmlWEB-INF | - web.xml - sun-web.xml - classes | - HelloWebServlet.java

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- HelloWebServlet.class

The code for the servlet, located in HelloWebServlet.java, is as follows:

import javax.servlet.http.*;import javax.servlet.*;import java.io.*;import java.sql.*;import javax.sql.*;import javax.naming.*;

public class HelloWebServlet extends HttpServlet {

InitialContext ctx = null; DataSource ds = null; Connection conn = null; PreparedStatement ps = null; ResultSet rs = null;

String sql = "SELECT Name, Population FROM Country WHERE Name=?";

public void init () throws ServletException { try { ctx = new InitialContext(); ds = (DataSource) ctx.lookup("java:comp/env/jdbc/MySQLDataSource"); conn = ds.getConnection(); ps = conn.prepareStatement(sql); } catch (SQLException se) { System.out.println("SQLException: "+se.getMessage()); } catch (NamingException ne) { System.out.println("NamingException: "+ne.getMessage()); } }

public void destroy () { try { if (rs != null) rs.close(); if (ps != null) ps.close(); if (conn != null) conn.close(); if (ctx != null) ctx.close(); } catch (SQLException se) { System.out.println("SQLException: "+se.getMessage()); } catch (NamingException ne) { System.out.println("NamingException: "+ne.getMessage()); } }

public void doPost(HttpServletRequest req, HttpServletResponse resp){ try { String country_name = req.getParameter("country_name"); resp.setContentType("text/html"); PrintWriter writer = resp.getWriter(); writer.println("<html><body>"); writer.println("<p>Country: "+country_name+"</p>"); ps.setString(1, country_name); rs = ps.executeQuery(); if (!rs.next()){ writer.println("<p>Country does not exist!</p>");

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} else { rs.beforeFirst(); while(rs.next()) { writer.println("<p>Name: "+rs.getString("Name")+"</p>"); writer.println("<p>Population: "+rs.getString("Population")+"</p>"); } } writer.println("</body></html>"); writer.close(); } catch (Exception e) { e.printStackTrace(); } }

public void doGet(HttpServletRequest req, HttpServletResponse resp){ try { resp.setContentType("text/html"); PrintWriter writer = resp.getWriter(); writer.println("<html><body>"); writer.println("<p>Hello from servlet doGet()</p>"); writer.println("</body></html>"); writer.close(); } catch (Exception e) { e.printStackTrace(); } }}

In the preceding code a basic doGet() method is implemented, but is not used in the example. Thecode to establish the connection with the database is as shown in the previous example, Section 14.1,“A Simple JSP Application with GlassFish, Connector/J and MySQL”, and is most conveniently located inthe servlet init() method. The corresponding freeing of resources is located in the destroy method. Themain functionality of the servlet is located in the doPost() method. If the user enters into the input forma country name that can be located in the database, the population of the country is returned. The code isinvoked using a POST action associated with the input form. The form is defined in the file index.html:

<html> <head><title>HelloWebServlet</title></head>

<body> <h1>HelloWebServlet</h1> <p>Please enter country name:</p> <form action="HelloWebServlet" method="POST"> <input type="text" name="country_name" length="50" /> <input type="submit" value="Submit" /> </form> </body></html>

The XML files web.xml and sun-web.xml are as for the example in the preceding section, Section 14.1,“A Simple JSP Application with GlassFish, Connector/J and MySQL”, no additional changes are required.

When compiling the Java source code, you will need to specify the path to the file javaee.jar. OnWindows, this can be done as follows:

$> javac -classpath c:\glassfishv3\glassfish\lib\javaee.jar HelloWebServlet.java

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Once the code is correctly located within its directory structure, and compiled, the application can bedeployed in GlassFish. This is done in exactly the same way as described in the preceding section,Section 14.1, “A Simple JSP Application with GlassFish, Connector/J and MySQL”.

Once deployed the application can be launched from within the GlassFish Administration Console. Enter acountry name such as “England”, and the application will return “Country does not exist!”. Enter “France”,and the application will return a population of 59225700.

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Chapter 15 Troubleshooting Connector/J ApplicationsThis section explains the symptoms and resolutions for the most commonly encountered issues withapplications using MySQL Connector/J.

Questions

• 15.1: When I try to connect to the database with MySQL Connector/J, I get the following exception:

SQLException: Server configuration denies access to data sourceSQLState: 08001VendorError: 0

What is going on? I can connect just fine with the MySQL command-line client.

• 15.2: My application throws an SQLException 'No Suitable Driver'. Why is this happening?

• 15.3: I'm trying to use MySQL Connector/J in an applet or application and I get an exception similar to:

SQLException: Cannot connect to MySQL server on host:3306.Is there a MySQL server running on the machine/port youare trying to connect to?

(java.security.AccessControlException)SQLState: 08S01VendorError: 0

• 15.4: I have a servlet/application that works fine for a day, and then stops working overnight

• 15.5: I'm trying to use JDBC 2.0 updatable result sets, and I get an exception saying my result set is notupdatable.

• 15.6: I cannot connect to the MySQL server using Connector/J, and I'm sure the connection parametersare correct.

• 15.7: My application is deployed through JBoss and I am using transactions to handle the statementson the MySQL database. Under heavy loads, I am getting an error and stack trace, but these only occurafter a fixed period of heavy activity.

• 15.8: When using gcj, a java.io.CharConversionException exception is raised when workingwith certain character sequences.

• 15.9: Updating a table that contains a primary key that is either FLOAT or compound primary key thatuses FLOAT fails to update the table and raises an exception.

• 15.10: You get an ER_NET_PACKET_TOO_LARGE exception, even though the binary blob size you wantto insert using JDBC is safely below the max_allowed_packet size.

• 15.11: What should you do if you receive error messages similar to the following: “Communications linkfailure – Last packet sent to the server was X ms ago”?

• 15.12: Why does Connector/J not reconnect to MySQL and re-issue the statement after acommunication failure, instead of throwing an Exception, even though I use the autoReconnectconnection string option?

• 15.13: How can I use 3-byte UTF8 with Connector/J?

• 15.14: How can I use 4-byte UTF8 (utf8mb4) with Connector/J?

• 15.15: Using useServerPrepStmts=false and certain character encodings can lead to corruptionwhen inserting BLOBs. How can this be avoided?

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/floating-point-types.html


https://docs.oracle.com/cd/E17952_01/mysql-errors-5.7-en/server-error-reference.html#error_er_net_packet_too_large

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/server-system-variables.html#sysvar_max_allowed_packet

Questions and Answers

15.1: When I try to connect to the database with MySQL Connector/J, I get the following exception:

SQLException: Server configuration denies access to data sourceSQLState: 08001VendorError: 0

What is going on? I can connect just fine with the MySQL command-line client.

MySQL Connector/J must use TCP/IP sockets to connect to MySQL, as Java does not support UnixDomain Sockets. Therefore, when MySQL Connector/J connects to MySQL, the security manager inMySQL server will use its grant tables to determine whether the connection is permitted.

You must add the necessary security credentials to the MySQL server for this to happen, using the GRANTstatement to your MySQL Server. See GRANT Statement, for more information.

Note

Testing your connectivity with the mysql command-line client will not work unlessyou add the "host" flag, and use something other than localhost for the host. Themysql command-line client will use Unix domain sockets if you use the special hostname localhost. If you are testing connectivity to localhost, use 127.0.0.1as the host name instead.

Warning

Changing privileges and permissions improperly in MySQL can potentially causeyour server installation to not have optimal security properties.

15.2: My application throws an SQLException 'No Suitable Driver'. Why is this happening?

There are three possible causes for this error:

• The Connector/J driver is not in your CLASSPATH, see Chapter 3, Connector/J Installation.

• The format of your connection URL is incorrect, or you are referencing the wrong JDBC driver.

• When using DriverManager, the jdbc.drivers system property has not been populated with thelocation of the Connector/J driver.

15.3: I'm trying to use MySQL Connector/J in an applet or application and I get an exception similarto:

SQLException: Cannot connect to MySQL server on host:3306.Is there a MySQL server running on the machine/port youare trying to connect to?

(java.security.AccessControlException)SQLState: 08S01VendorError: 0

Either you're running an Applet, your MySQL server has been installed with the skip_networkingsystem variable enabled, or your MySQL server has a firewall sitting in front of it.

Applets can only make network connections back to the machine that runs the web server that servedthe .class files for the applet. This means that MySQL must run on the same machine (or you must havesome sort of port re-direction) for this to work. This also means that you will not be able to test applets fromyour local file system, you must always deploy them to a web server.

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/grant.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/grant.html

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/server-system-variables.html#sysvar_skip_networking

MySQL Connector/J can only communicate with MySQL using TCP/IP, as Java does not support Unixdomain sockets. TCP/IP communication with MySQL might be affected if MySQL was started with theskip_networking system variable enabled, or if it is firewalled.

If MySQL has been started with skip_networking enabled (the Debian Linux package of MySQL serverdoes this for example), you need to comment it out in the file /etc/mysql/my.cnf or /etc/my.cnf.Of course your my.cnf file might also exist in the data directory of your MySQL server, or anywhereelse (depending on how MySQL was compiled for your system). Binaries created by us always look in /etc/my.cnf and datadir/my.cnf. If your MySQL server has been firewalled, you will need to havethe firewall configured to allow TCP/IP connections from the host where your Java code is running to theMySQL server on the port that MySQL is listening to (by default, 3306).

15.4: I have a servlet/application that works fine for a day, and then stops working overnight

MySQL closes connections after 8 hours of inactivity. You either need to use a connection pool thathandles stale connections or use the autoReconnect parameter (see Section 5.3, “ConfigurationProperties for Connector/J”).

Also, catch SQLExceptions in your application and deal with them, rather than propagating them allthe way until your application exits. This is just good programming practice. MySQL Connector/J will setthe SQLState (see java.sql.SQLException.getSQLState() in your API docs) to 08S01 when itencounters network-connectivity issues during the processing of a query. Attempt to reconnect to MySQLat this point.

The following (simplistic) example shows what code that can handle these exceptions might look like:

Example 15.1 Connector/J: Example of transaction with retry logic

public void doBusinessOp() throws SQLException { Connection conn = null; Statement stmt = null; ResultSet rs = null;

// // How many times do you want to retry the transaction // (or at least _getting_ a connection)? // int retryCount = 5;

boolean transactionCompleted = false;

do { try { conn = getConnection(); // assume getting this from a // javax.sql.DataSource, or the // java.sql.DriverManager

conn.setAutoCommit(false);

// // Okay, at this point, the 'retry-ability' of the // transaction really depends on your application logic, // whether or not you're using autocommit (in this case // not), and whether you're using transactional storage // engines // // For this example, we'll assume that it's _not_ safe // to retry the entire transaction, so we set retry // count to 0 at this point // // If you were using exclusively transaction-safe tables, // or your application could recover from a connection going // bad in the middle of an operation, then you would not

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// touch 'retryCount' here, and just let the loop repeat // until retryCount == 0. // retryCount = 0;


String query = "SELECT foo FROM bar ORDER BY baz";

rs = stmt.executeQuery(query);

while (rs.next()) { }

rs.close(); rs = null;

stmt.close(); stmt = null;

conn.commit(); conn.close(); conn = null;

transactionCompleted = true; } catch (SQLException sqlEx) {

// // The two SQL states that are 'retry-able' are 08S01 // for a communications error, and 40001 for deadlock. // // Only retry if the error was due to a stale connection, // communications problem or deadlock //

String sqlState = sqlEx.getSQLState();

if ("08S01".equals(sqlState) || "40001".equals(sqlState)) { retryCount -= 1; } else { retryCount = 0; } } finally { if (rs != null) { try { rs.close(); } catch (SQLException sqlEx) { // You'd probably want to log this... } }

if (stmt != null) { try { stmt.close(); } catch (SQLException sqlEx) { // You'd probably want to log this as well... } }

if (conn != null) { try { // // If we got here, and conn is not null, the // transaction should be rolled back, as not // all work has been done

try {

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conn.rollback(); } finally { conn.close(); } } catch (SQLException sqlEx) { // // If we got an exception here, something // pretty serious is going on, so we better // pass it up the stack, rather than just // logging it...

throw sqlEx; } } } } while (!transactionCompleted && (retryCount > 0));}

Note

Use of the autoReconnect option is not recommended because there is no safemethod of reconnecting to the MySQL server without risking some corruption ofthe connection state or database state information. Instead, use a connectionpool, which will enable your application to connect to the MySQL server using anavailable connection from the pool. The autoReconnect facility is deprecated, andmay be removed in a future release.

15.5: I'm trying to use JDBC 2.0 updatable result sets, and I get an exception saying my result setis not updatable.

Because MySQL does not have row identifiers, MySQL Connector/J can only update result sets that havecome from queries on tables that have at least one primary key, the query must select every primary keycolumn, and the query can only span one table (that is, no joins). This is outlined in the JDBC specification.

Note that this issue only occurs when using updatable result sets, and is caused because Connector/J isunable to guarantee that it can identify the correct rows within the result set to be updated without havinga unique reference to each row. There is no requirement to have a unique field on a table if you are usingUPDATE or DELETE statements on a table where you can individually specify the criteria to be matchedusing a WHERE clause.

15.6: I cannot connect to the MySQL server using Connector/J, and I'm sure the connectionparameters are correct.

Make sure that the skip_networking system variable has not been enabled on your server. Connector/J must be able to communicate with your server over TCP/IP; named sockets are not supported. Alsoensure that you are not filtering connections through a firewall or other network security system. For moreinformation, see Can't connect to [local] MySQL server.

15.7: My application is deployed through JBoss and I am using transactions to handle thestatements on the MySQL database. Under heavy loads, I am getting an error and stack trace, butthese only occur after a fixed period of heavy activity.

This is a JBoss, not Connector/J, issue and is connected to the use of transactions. Under heavy loads thetime taken for transactions to complete can increase, and the error is caused because you have exceededthe predefined timeout.

You can increase the timeout value by setting the TransactionTimeout attribute to theTransactionManagerService within the /conf/jboss-service.xml file (pre-4.0.3) or /deploy/jta-service.xml for JBoss 4.0.3 or later. See TransactionTimeout within the JBoss wiki for moreinformation.

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/can-not-connect-to-server.html

http://wiki.jboss.org/wiki/Wiki.jsp?page=TransactionTimeout

15.8: When using gcj, a java.io.CharConversionException exception is raised when workingwith certain character sequences.

This is a known issue with gcj which raises an exception when it reaches an unknown character or oneit cannot convert. Add useJvmCharsetConverters=true to your connection string to force characterconversion outside of the gcj libraries, or try a different JDK.

15.9: Updating a table that contains a primary key that is either FLOAT or compound primary keythat uses FLOAT fails to update the table and raises an exception.

Connector/J adds conditions to the WHERE clause during an UPDATE to check the old values of the primarykey. If there is no match, then Connector/J considers this a failure condition and raises an exception.

The problem is that rounding differences between supplied values and the values stored in the databasemay mean that the values never match, and hence the update fails. The issue will affect all queries, notjust those from Connector/J.

To prevent this issue, use a primary key that does not use FLOAT. If you have to use a floating pointcolumn in your primary key, use DOUBLE or DECIMAL types in place of FLOAT.

15.10: You get an ER_NET_PACKET_TOO_LARGE exception, even though the binary blob size youwant to insert using JDBC is safely below the max_allowed_packet size.

This is because the hexEscapeBlock() method incom.mysql.jdbc.PreparedStatement.streamToBytes() may almost double the size of your data.

15.11: What should you do if you receive error messages similar to the following:“Communications link failure – Last packet sent to the server was X ms ago”?

Generally speaking, this error suggests that the network connection has been closed. There can be severalroot causes:

• Firewalls or routers may clamp down on idle connections (the MySQL client/server protocol does notping).

• The MySQL Server may be closing idle connections that exceed the wait_timeout orinteractive_timeout threshold.

To help troubleshoot these issues, the following tips can be used. If a recent (5.1.13+) version ofConnector/J is used, you will see an improved level of information compared to earlier versions. Olderversions simply display the last time a packet was sent to the server, which is frequently 0 ms ago. Thisis of limited use, as it may be that a packet was just sent, while a packet from the server has not beenreceived for several hours. Knowing the period of time since Connector/J last received a packet from theserver is useful information, so if this is not displayed in your exception message, it is recommended thatyou update Connector/J.

Further, if the time a packet was last sent/received exceeds the wait_timeout orinteractive_timeout threshold, this is noted in the exception message.

Although network connections can be volatile, the following can be helpful in avoiding problems:

• Ensure connections are valid when used from the connection pool. Use a query that starts with /* ping*/ to execute a lightweight ping instead of full query. Note, the syntax of the ping needs to be exactly asspecified here.

• Minimize the duration a connection object is left idle while other application logic is executed.

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https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/fixed-point-types.html


https://docs.oracle.com/cd/E17952_01/mysql-errors-5.7-en/server-error-reference.html#error_er_net_packet_too_large

https://docs.oracle.com/cd/E17952_01/mysql-5.7-en/server-system-variables.html#sysvar_max_allowed_packet

• Explicitly validate the connection before using it if the connection has been left idle for an extendedperiod of time.

• Ensure that wait_timeout and interactive_timeout are set sufficiently high.

• Ensure that tcpKeepalive is enabled.

• Ensure that any configurable firewall or router timeout settings allow for the maximum expectedconnection idle time.

Note

Do not expect to be able to reuse a connection without problems, if it has beinglying idle for a period. If a connection is to be reused after being idle for any lengthof time, ensure that you explicitly test it before reusing it.

15.12: Why does Connector/J not reconnect to MySQL and re-issue the statement after acommunication failure, instead of throwing an Exception, even though I use the autoReconnectconnection string option?

There are several reasons for this. The first is transactional integrity. The MySQL Reference Manual statesthat “there is no safe method of reconnecting to the MySQL server without risking some corruption of theconnection state or database state information”. Consider the following series of statements for example:

conn.createStatement().execute( "UPDATE checking_account SET balance = balance - 1000.00 WHERE customer='Smith'");conn.createStatement().execute( "UPDATE savings_account SET balance = balance + 1000.00 WHERE customer='Smith'");conn.commit();

Consider the case where the connection to the server fails after the UPDATE to checking_account.If no exception is thrown, and the application never learns about the problem, it will continue executing.However, the server did not commit the first transaction in this case, so that will get rolled back. Butexecution continues with the next transaction, and increases the savings_account balance by 1000.The application did not receive an exception, so it continued regardless, eventually committing the secondtransaction, as the commit only applies to the changes made in the new connection. Rather than a transfertaking place, a deposit was made in this example.

Note that running with autocommit enabled does not solve this problem. When Connector/J encountersa communication problem, there is no means to determine whether the server processed the currentlyexecuting statement or not. The following theoretical states are equally possible:

• The server never received the statement, and therefore no related processing occurred on the server.

• The server received the statement, executed it in full, but the response was not received by the client.

If you are running with autocommit enabled, it is not possible to guarantee the state of data on the serverwhen a communication exception is encountered. The statement may have reached the server, or it maynot. All you know is that communication failed at some point, before the client received confirmation (ordata) from the server. This does not only affect autocommit statements though. If the communicationproblem occurred during Connection.commit(), the question arises of whether the transaction wascommitted on the server before the communication failed, or whether the server received the commitrequest at all.

The second reason for the generation of exceptions is that transaction-scoped contextual data may bevulnerable, for example:

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• Temporary tables.

• User-defined variables.

• Server-side prepared statements.

These items are lost when a connection fails, and if the connection silently reconnects without generatingan exception, this could be detrimental to the correct execution of your application.

In summary, communication errors generate conditions that may well be unsafe for Connector/J to simplyignore by silently reconnecting. It is necessary for the application to be notified. It is then for the applicationdeveloper to decide how to proceed in the event of connection errors and failures.

15.13: How can I use 3-byte UTF8 with Connector/J?

For 5.1.46 and earlier: To use 3-byte UTF8 with Connector/J set characterEncoding=utf8 and setuseUnicode=true in the connection string.

For 5.1.47 and later: Because there is no Java-style character set name for utfmb3 that you can usewith the connection option charaterEncoding, the only way to use utf8mb3 as your connectioncharacter set is to use a utf8mb3 collation (for example, utf8_general_ci) for the connection optionconnectionCollation, which forces a utf8mb3 character set to be used. See Section 5.6, “UsingCharacter Sets and Unicode” for details.

15.14: How can I use 4-byte UTF8 (utf8mb4) with Connector/J?

To use 4-byte UTF8 with Connector/J configure the MySQL server withcharacter_set_server=utf8mb4. Connector/J will then use that setting, if characterEncoding andconnectionCollation have not been set in the connection string. This is equivalent to autodetectionof the character set. See Section 5.6, “Using Character Sets and Unicode” for details. For 5.1.47 and later:You can use characterEncoding=UTF-8 to use utf8mb4, even if character_set_server on theserver has been set to something else.

15.15: Using useServerPrepStmts=false and certain character encodings can lead to corruptionwhen inserting BLOBs. How can this be avoided?

When using certain character encodings, such as SJIS, CP932, and BIG5, it is possible that BLOB datacontains characters that can be interpreted as control characters, for example, backslash, '\'. This can leadto corrupted data when inserting BLOBs into the database. There are two things that need to be done toavoid this:

1. Set the connection string option useServerPrepStmts to true.

2. Set SQL_MODE to NO_BACKSLASH_ESCAPES.

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Chapter 16 Known Issues and LimitationsThe following are some known issues and limitations for MySQL Connector/J 5.1:

• When Connector/J retrieves timestamps for a daylight saving time (DST) switch day using thegetTimeStamp() method on the result set, some of the returned values might be wrong. The errorscan be avoided by using the following connection options when connecting to a database:

useTimezone=true useLegacyDatetimeCode=false serverTimezone=UTC

• Since release 5.1.41, the functionality of the property elideSetAutoCommits has been disabled dueto Bug# 66884. Any value given for the property is ignored by Connector/J.

• MySQL Server uses a proleptic Gregorian calendar internally. However, Connector/J usesjava.sql.Date, which is non-proleptic. Therefore, when setting and retrieving dates that were beforethe Julian-Gregorian cutover (October 15, 1582) using the PreparedStatement methods, alwayssupply explicitly a proleptic Gregorian calendar to the setDate() and getDate() methods, in order toavoid possible errors with dates stored to and calculated by the server.

• For MySQL 8.0.14 and later, 5.7.25 and later, and 5.6.43 and later: To use Windows named pipes forconnections, the MySQL Server that Connector/J wants to connect to must be started with the systemvariable named_pipe_full_access_group; see Section 5.9, “Connecting Using Named Pipes” fordetails.

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Chapter 17 Connector/J Support

Table of Contents17.1 Connector/J Community Support ............................................................................................. 13317.2 How to Report Connector/J Bugs or Problems ......................................................................... 133

17.1 Connector/J Community Support

You can join the #connectors channel in the MySQL Community Slack workspace, where you can gethelp directly from MySQL developers and other users.

17.2 How to Report Connector/J Bugs or Problems

The normal place to report bugs is http://bugs.mysql.com/, which is the address for our bugs database.This database is public, and can be browsed and searched by anyone. If you log in to the system, you willalso be able to enter new reports.

If you find a sensitive security bug in MySQL Server, please let us know immediately by sending an emailmessage to <[email protected]>. Exception: Support customers should report all problems,including security bugs, to Oracle Support at http://support.oracle.com/.

Writing a good bug report takes patience, but doing it right the first time saves time both for us and foryourself. A good bug report, containing a full test case for the bug, makes it very likely that we will fix thebug in the next release.

This section will help you write your report correctly so that you do not waste your time doing things thatmay not help us much or at all.

If you have a repeatable bug report, please report it to the bugs database at http://bugs.mysql.com/. Anybug that we are able to repeat has a high chance of being fixed in the next MySQL release.

To report other problems, you can use one of the MySQL mailing lists.

Remember that it is possible for us to respond to a message containing too much information, but not toone containing too little. People often omit facts because they think they know the cause of a problem andassume that some details do not matter.

A good principle is this: If you are in doubt about stating something, state it. It is faster and lesstroublesome to write a couple more lines in your report than to wait longer for the answer if we must askyou to provide information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the version number of Connector/J orMySQL used, and (b) not fully describing the platform on which Connector/J is installed (including the JVMversion, and the platform type and version number that MySQL itself is installed on).

This is highly relevant information, and in 99 cases out of 100, the bug report is useless without it. Veryoften we get questions like, “Why doesn't this work for me?” Then we find that the feature requested wasn'timplemented in that MySQL version, or that a bug described in a report has already been fixed in newerMySQL versions.

Sometimes the error is platform-dependent; in such cases, it is next to impossible for us to fix anythingwithout knowing the operating system and the version number of the platform.

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https://mysqlcommunity.slack.com/messages/connectors

http://bugs.mysql.com/

http://support.oracle.com/


How to Report Connector/J Bugs or Problems

If at all possible, create a repeatable, standalone testcase that doesn't involve any third-party classes.

To streamline this process, we ship a base class for testcases with Connector/J, named'com.mysql.jdbc.util.BaseBugReport'. To create a testcase for Connector/J using this class, createyour own class that inherits from com.mysql.jdbc.util.BaseBugReport and override the methodssetUp(), tearDown() and runTest().

In the setUp() method, create code that creates your tables, and populates them with any data needed todemonstrate the bug.

In the runTest() method, create code that demonstrates the bug using the tables and data you createdin the setUp method.

In the tearDown() method, drop any tables you created in the setUp() method.

In any of the above three methods, use one of the variants of the getConnection() method to create aJDBC connection to MySQL:

• getConnection() - Provides a connection to the JDBC URL specified in getUrl(). If a connectionalready exists, that connection is returned, otherwise a new connection is created.

• getNewConnection() - Use this if you need to get a new connection for your bug report (that is, thereis more than one connection involved).

• getConnection(String url) - Returns a connection using the given URL.

• getConnection(String url, Properties props) - Returns a connection using the given URLand properties.

If you need to use a JDBC URL that is different from 'jdbc:mysql:///test', override the method getUrl() aswell.

Use the assertTrue(boolean expression) and assertTrue(String failureMessage,boolean expression) methods to create conditions that must be met in your testcase demonstratingthe behavior you are expecting (vs. the behavior you are observing, which is why you are most likely filinga bug report).

Finally, create a main() method that creates a new instance of your testcase, and calls the run method:

public static void main(String[] args) throws Exception { new MyBugReport().run(); }

Once you have finished your testcase, and have verified that it demonstrates the bug you are reporting,upload it with your bug report to http://bugs.mysql.com/.

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Index

AallowLoadLocalInfile connection property, 28allowMasterDownConnections connection property, 25allowMultiQueries connection property, 26allowNanAndInf connection property, 41allowPublicKeyRetrieval connection property, 29allowSlaveDownConnections connection property, 25allowUrlInLocalInfile connection property, 28alwaysSendSetIsolation connection property, 30authenticationPlugins connection property, 21autoClosePStmtStreams connection property, 41autoDeserialize connection property, 41autoGenerateTestcaseScript connection property, 37autoReconnect connection property, 23autoReconnectForPools connection property, 24autoSlowLog connection property, 37

BblobsAreStrings connection property, 42blobSendChunkSize connection property, 31

CcacheCallableStmts connection property, 31cacheDefaultTimezone connection property, 42cachePrepStmts connection property, 31cacheResultSetMetadata connection property, 31cacheServerConfiguration connection property, 32callableStmtCacheSize connection property, 29capitalizeTypeNames connection property, 42character sets

with Connector/J, 60characterEncoding connection property, 39characterSetResults connection property, 40clientCertificateKeyStorePassword connection property,27clientCertificateKeyStoreType connection property, 27clientCertificateKeyStoreUrl connection property, 27clientInfoProvider connection property, 37clobberStreamingResults connection property, 42clobCharacterEncoding connection property, 42collation

of connection character set, 60compensateOnDuplicateKeyUpdateCounts connectionproperty, 42connecting

through JDBC and Connector/J, 17with Unix domain socket, 65with Windows named pipes, 65, 131

connection pooling, 85, 113, 115connection URL, 17

connectionAttributes connection property, 40connectionCollation connection property, 40connectionLifecycleInterceptors connection property, 21Connector/J

known issues, 131limitations, 131reporting problems, 133troubleshooting, 123

connectTimeout connection property, 20continueBatchOnError connection property, 43createDatabaseIfNotExist connection property, 43

DdefaultAuthenticationPlugin connection property, 21defaultFetchSize connection property, 32detectCustomCollations connection property, 43disabledAuthenticationPlugins connection property, 21disconnectOnExpiredPasswords connection property, 22dontCheckOnDuplicateKeyUpdateInSQL connectionproperty, 32dontTrackOpenResources connection property, 32dumpMetadataOnColumnNotFound connection property,37dumpQueriesOnException connection property, 38dynamicCalendars connection property, 32

EelideSetAutoCommits connection property, 32emptyStringsConvertToZero connection property, 43emulateLocators connection property, 43emulateUnsupportedPstmts connection property, 43enabledSSLCipherSuites connection property, 28enabledTLSProtocols connection property, 28enableEscapeProcessing connection property, 33enablePacketDebug connection property, 38enableQueryTimeouts connection property, 33error codes, 67ER_ABORTING_CONNECTION, 67ER_ACCESS_DENIED_ERROR, 67ER_BAD_FIELD_ERROR, 67ER_BAD_HOST_ERROR, 67ER_BAD_TABLE_ERROR, 67ER_BLOBS_AND_NO_TERMINATED, 67ER_BLOB_CANT_HAVE_DEFAULT, 67ER_BLOB_KEY_WITHOUT_LENGTH, 67ER_BLOB_USED_AS_KEY, 67ER_CANT_DO_THIS_DURING_AN_TRANSACTION, 67ER_CANT_DROP_FIELD_OR_KEY, 67ER_CANT_REMOVE_ALL_FIELDS, 67ER_CANT_USE_OPTION_HERE, 67ER_CHECK_NOT_IMPLEMENTED, 67ER_CHECK_NO_SUCH_TABLE, 67ER_COLLATION_CHARSET_MISMATCH, 67

135

ER_COLUMNACCESS_DENIED_ERROR, 67ER_CONNECT_TO_MASTER, 67ER_CON_COUNT_ERROR, 67ER_DBACCESS_DENIED_ERROR, 67ER_DERIVED_MUST_HAVE_ALIAS, 67ER_DUP_ENTRY, 67ER_DUP_FIELDNAME, 67ER_DUP_KEY, 67ER_DUP_KEYNAME, 67ER_DUP_UNIQUE, 67ER_EMPTY_QUERY, 67ER_FIELD_SPECIFIED_TWICE, 67ER_FORCING_CLOSE, 67ER_GRANT_WRONG_HOST_OR_USER, 67ER_HANDSHAKE_ERROR, 67ER_HOST_IS_BLOCKED, 67ER_HOST_NOT_PRIVILEGED, 67ER_ILLEGAL_GRANT_FOR_TABLE, 67ER_ILLEGAL_REFERENCE, 67ER_INVALID_DEFAULT, 67ER_INVALID_USE_OF_NULL, 67ER_IPSOCK_ERROR, 67ER_KEY_COLUMN_DOES_NOT_EXITS, 67ER_LOCK_DEADLOCK, 67ER_LOCK_WAIT_TIMEOUT, 67ER_MASTER_NET_READ, 67ER_MASTER_NET_WRITE, 67ER_MIX_OF_GROUP_FUNC_AND_FIELDS, 67ER_MULTIPLE_PRI_KEY, 67ER_NET_ERROR_ON_WRITE, 67ER_NET_FCNTL_ERROR, 67ER_NET_PACKETS_OUT_OF_ORDER, 67ER_NET_PACKET_TOO_LARGE, 67ER_NET_READ_ERROR, 67ER_NET_READ_ERROR_FROM_PIPE, 67ER_NET_READ_INTERRUPTED, 67ER_NET_UNCOMPRESS_ERROR, 67ER_NET_WRITE_INTERRUPTED, 67ER_NEW_ABORTING_CONNECTION, 67ER_NONEXISTING_GRANT, 67ER_NONEXISTING_TABLE_GRANT, 67ER_NONUNIQ_TABLE, 67ER_NON_UNIQ_ERROR, 67ER_NOT_ALLOWED_COMMAND, 67ER_NOT_SUPPORTED_AUTH_MODE, 67ER_NOT_SUPPORTED_YET, 67ER_NO_DEFAULT, 67ER_NO_PERMISSION_TO_CREATE_USER, 67ER_NO_REFERENCED_ROW, 67ER_NO_SUCH_INDEX, 67ER_NO_SUCH_TABLE, 67ER_NULL_COLUMN_IN_INDEX, 67ER_OPERAND_COLUMNS, 67ER_OUTOFMEMORY, 67

ER_OUT_OF_SORTMEMORY, 67ER_PARSE_ERROR, 67ER_PASSWORD_ANONYMOUS_USER, 67ER_PASSWORD_NOT_ALLOWED, 67ER_PASSWORD_NO_MATCH, 67ER_PRIMARY_CANT_HAVE_NULL, 67ER_READ_ONLY_TRANSACTION, 67ER_REGEXP_ERROR, 67ER_REQUIRES_PRIMARY_KEY, 67ER_ROW_IS_REFERENCED, 67ER_SELECT_REDUCED, 67ER_SERVER_SHUTDOWN, 67ER_SPATIAL_CANT_HAVE_NULL, 67ER_SUBQUERY_NO_1_ROW, 67ER_SYNTAX_ERROR, 67ER_TABLEACCESS_DENIED_ERROR, 67ER_TABLENAME_NOT_ALLOWED_HERE, 67ER_TABLE_CANT_HANDLE_AUTO_INCREMENT, 67ER_TABLE_CANT_HANDLE_BLOB, 67ER_TABLE_EXISTS_ERROR, 67ER_TABLE_MUST_HAVE_COLUMNS, 67ER_TOO_BIG_FIELDLENGTH, 67ER_TOO_BIG_ROWSIZE, 67ER_TOO_BIG_SELECT, 67ER_TOO_LONG_IDENT, 67ER_TOO_LONG_KEY, 67ER_TOO_LONG_STRING, 67ER_TOO_MANY_KEYS, 67ER_TOO_MANY_KEY_PARTS, 67ER_TOO_MANY_ROWS, 67ER_TOO_MANY_USER_CONNECTIONS, 67ER_UNKNOWN_CHARACTER_SET, 67ER_UNKNOWN_COM_ERROR, 67ER_UNKNOWN_PROCEDURE, 67ER_UNKNOWN_STORAGE_ENGINE, 67ER_UNKNOWN_TABLE, 67ER_UNSUPPORTED_EXTENSION, 67ER_USER_LIMIT_REACHED, 67ER_WARN_DATA_OUT_OF_RANGE, 67ER_WARN_DATA_TRUNCATED, 67ER_WARN_NULL_TO_NOTNULL, 67ER_WARN_TOO_FEW_RECORDS, 67ER_WARN_TOO_MANY_RECORDS, 67ER_WRONG_AUTO_KEY, 67ER_WRONG_COLUMN_NAME, 67ER_WRONG_DB_NAME, 67ER_WRONG_FIELD_SPEC, 67ER_WRONG_FIELD_TERMINATORS, 67ER_WRONG_FIELD_WITH_GROUP, 67ER_WRONG_FK_DEF, 67ER_WRONG_GROUP_FIELD, 67ER_WRONG_KEY_COLUMN, 67ER_WRONG_NAME_FOR_CATALOG, 67ER_WRONG_NAME_FOR_INDEX, 67

136

ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,67ER_WRONG_OUTER_JOIN, 67ER_WRONG_PARAMCOUNT_TO_PROCEDURE, 67ER_WRONG_SUM_SELECT, 67ER_WRONG_TABLE_NAME, 67ER_WRONG_TYPE_FOR_VAR, 67ER_WRONG_VALUE_COUNT, 67ER_WRONG_VALUE_COUNT_ON_ROW, 67ER_WRONG_VALUE_FOR_VAR, 67exceptionInterceptors connection property, 44explainSlowQueries connection property, 38

Ffailover

Java clients, 89failOverReadOnly connection property, 24functionsNeverReturnBlobs connection property, 44

GgatherPerfMetrics connection property, 36generateSimpleParameterMetadata connection property,44getProceduresReturnsFunctions connection property, 44GlassFish application server, 115

HholdResultsOpenOverStatementClose connectionproperty, 33

IignoreNonTxTables connection property, 44includeInnodbStatusInDeadlockExceptions connectionproperty, 38includeThreadDumpInDeadlockExceptions connectionproperty, 38includeThreadNamesAsStatementComment connectionproperty, 38initialTimeout connection property, 24interactiveClient connection property, 22

JJ2EE

connection pooling, 85load balancing, 92

JBoss application server, 107JDBC

and MySQL data types, 57background information for Connector/J, 75character sets, 60CLASSPATH, 5code examples, 15

compatibility, 54configuration properties, 19driver for MySQL, 1SQLState codes, 67troubleshooting, 7, 123, 131versions supported, 3

jdbcCompliantTruncation connection property, 44

Kknown issues

Connector/J, 131

LlargeRowSizeThreshold connection property, 33limitations

Connector/J, 131load balancing

with Connector/J, 92, 94loadBalanceAutoCommitStatementRegex connectionproperty, 45loadBalanceAutoCommitStatementThreshold connectionproperty, 45loadBalanceBlacklistTimeout connection property, 45loadBalanceConnectionGroup connection property, 45loadBalanceEnableJMX connection property, 41loadBalanceExceptionChecker connection property, 45loadBalanceHostRemovalGracePeriod connectionproperty, 41loadBalancePingTimeout connection property, 45loadBalanceSQLExceptionSubclassFailover connectionproperty, 46loadBalanceSQLStateFailover connection property, 46loadBalanceStrategy connection property, 33loadBalanceValidateConnectionOnSwapServerconnection property, 46localSocketAddress connection property, 22locatorFetchBufferSize connection property, 34logger connection property, 35loggers, 103logging, 103logSlowQueries connection property, 38logXaCommands connection property, 39

MmaintainTimeStats connection property, 31maxAllowedPacket connection property, 23maxQuerySizeToLog connection property, 36maxReconnects connection property, 24maxRows connection property, 46metadataCacheSize connection property, 29multi-host connections

with Connector/J, 89

137

Nnamed pipes, 65, 131netTimeoutForStreamingResults connection property, 46noAccessToProcedureBodies connection property, 46noDatetimeStringSync connection property, 47noTimezoneConversionForDateType connectionproperty, 47noTimezoneConversionForTimeType connectionproperty, 47nullCatalogMeansCurrent connection property, 47nullNamePatternMatchesAll connection property, 47

OoverrideSupportsIntegrityEnhancementFacilityconnection property, 47

PpacketDebugBufferSize connection property, 36padCharsWithSpace connection property, 48PAM authentication

with Connector/J, 66paranoid connection property, 29parseInfoCacheFactory connection property, 30password connection property, 20passwordCharacterEncoding connection property, 29pedantic connection property, 48pinGlobalTxToPhysicalConnection connection property,48populateInsertRowWithDefaultValues connectionproperty, 48prepStmtCacheSize connection property, 30prepStmtCacheSqlLimit connection property, 30processEscapeCodesForPrepStmts connection property,48profilerEventHandler connection property, 39profileSQL connection property, 36profileSql connection property, 36proleptic Gregorian calendar, 131propertiesTransform connection property, 22

QqueriesBeforeRetryMaster connection property, 25queryTimeoutKillsConnection connection property, 48

RreadFromMasterWhenNoSlaves connection property, 26readOnlyPropagatesToServer connection property, 34reconnectAtTxEnd connection property, 24relaxAutoCommit connection property, 48replication

with Connector/J, 94replicationConnectionGroup connection property, 26

replicationEnableJMX connection property, 26reportMetricsIntervalMillis connection property, 36requireSSL connection property, 27resourceId connection property, 26resultSetSizeThreshold connection property, 39retainStatementAfterResultSetClose connection property,49retriesAllDown connection property, 24rewriteBatchedStatements connection property, 34rollbackOnPooledClose connection property, 49roundRobinLoadBalance connection property, 25runningCTS13 connection property, 49

SsecondsBeforeRetryMaster connection property, 25selfDestructOnPingMaxOperations connection property,26selfDestructOnPingSecondsLifetime connection property,26sendFractionalSeconds connection property, 49serverAffinityOrder connection property, 34serverConfigCacheFactory connection property, 30serverRSAPublicKeyFile connection property, 29serverTimezone connection property, 49servlet, 118sessionVariables connection property, 41SLF4J, 103slowQueryThresholdMillis connection property, 36slowQueryThresholdNanos connection property, 37socketFactory connection property, 20socketTimeout connection property, 21socksProxyHost connection property, 22socksProxyPort connection property, 22Spring framework, 109SQLState error codes, 67SSL, 61statementInterceptors connection property, 49strictFloatingPoint connection property, 50strictUpdates connection property, 50

TtcpKeepAlive connection property, 23tcpNoDelay connection property, 23tcpRcvBuf connection property, 23tcpSndBuf connection property, 23tcpTrafficClass connection property, 23tinyInt1isBit connection property, 50Tomcat application server, 105traceProtocol connection property, 39transformedBitIsBoolean connection property, 50treatUtilDateAsTimestamp connection property, 50troubleshooting

Connector/J, 123

138

JDBC, 7JDBC SQLState codes, 67

trustCertificateKeyStorePassword connection property,28trustCertificateKeyStoreType connection property, 28trustCertificateKeyStoreUrl connection property, 28

UultraDevHack connection property, 50Unicode

with Connector/J, 60Unix doman socket, 65useAffectedRows connection property, 50useBlobToStoreUTF8OutsideBMP connection property,40useColumnNamesInFindColumn connection property, 41useCompression connection property, 22useConfigs connection properties, 53useConfigs connection property, 21useCursorFetch connection property, 31useDirectRowUnpack connection property, 35useDynamicCharsetInfo connection property, 35useFastDateParsing connection property, 35useFastIntParsing connection property, 35useGmtMillisForDatetimes connection property, 51useHostsInPrivileges connection property, 51useInformationSchema connection property, 51useJDBCCompliantTimezoneShift connection property,51useJvmCharsetConverters connection property, 35useLegacyDatetimeCode connection property, 51useLocalSessionState connection property, 29useLocalTransactionState connection property, 30useNanosForElapsedTime connection property, 39useOldAliasMetadataBehavior connection property, 52useOldUTF8Behavior connection property, 52useOnlyServerErrorMessages connection property, 52user connection property, 20useReadAheadInput connection property, 35useServerPrepStmts connection property, 52useSqlStateCodes connection property, 52useSSL connection property, 27useSSPSCompatibleTimezoneShift connection property,52useStreamLengthsInPrepStmts connection property, 52useTimezone connection property, 53useUnbufferedInput connection property, 53useUnicode connection property, 39useUsageAdvisor connection property, 37utf8OutsideBmpExcludedColumnNamePatternconnection property, 40utf8OutsideBmpIncludedColumnNamePattern connectionproperty, 40

VverifyServerCertificate connection property, 27

YyearIsDateType connection property, 53

ZzeroDateTimeBehavior connection property, 53

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mysql connector/j 5.1 developer guide

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